BENGHAZI, Libya (Reuters) - Western powers have destroyed nearly a third of Libyan leader Muammar Gaddafi's military since launching air strikes last month but NATO said it was forced to change bombing tactics because of human shields.
The besieged city of Misrata, the only big population center in western Libya where a revolt against Gaddafi has not been crushed and which faces army tanks and snipers, is now the priority for NATO air strikes.
But Libyan rebels on the battlefield complained about what they see as a dropping off in air support and a spokesman in the rebel stronghold of Benghazi said NATO "disappointed us" with its slow response that allowed Gaddafi forces to kill people.
"Either NATO does its work properly or we will ask the Security Council to suspend its work," said Abdel Fattah Younes, head of the rebel forces. "NATO is moving very slowly, allowing Gaddafi forces to advance," he told reporters.
"NATO has become our problem," he said, adding that NATO inaction was allowing the army to advance and letting them kill the people of Misrata "every day."
As the row erupted over the military campaign, the International Criminal Court said on Tuesday it had evidence Gaddafi's government had developed plans to crush protests by killing civilians even before the uprising in Libya broke out.
"We have evidence that after the Tunisia and Egypt conflicts in January, people in the regime were planning how to control demonstrations inside Libya," court prosecutor Luis Moreno-Ocampo told Reuters in The Hague.
"The planning at the beginning was to use tear gas and (if that failed to work) ..., shooting," said Moreno-Ocampo who is investigating Gaddafi, his sons and close aides and who will be requesting arrest warrants in the coming weeks.
Protests against the government that began on February 15 swiftly descended into civil war after Gaddafi forces opened fire on demonstrators. He then crushed uprisings in Libya's west, leaving the east and Misrata in rebel hands.
NATO-led air power is now holding the balance in Libya, preventing Gaddafi forces from overrunning the revolt in the North African desert state but unable for now to hand the rebels outright victory with a stalemate on the desert battlefield.
NATO took command of operations in Libya from a coalition led by the United States, Britain and France on March 31 and is enforcing a no-fly zone ordered by the United Nations and launching air strikes on Gaddafi forces to protect civilians.
"The assessment is that we have taken out 30 percent of the military capacity of Gaddafi," Brigadier General Mark van Uhm, a senior NATO staff officer, said in Brussels.
Over the last day, air strikes around Misrata hit Gaddafi's tanks, air defense systems and other armored vehicles. Near Brega in the east, where intense fighting raged for a sixth day on Tuesday, NATO aircraft struck a rocket launcher.
Answering earlier criticism by insurgents that air power became less effective with the alliance in control, NATO officials said the presence in Libyan skies was undiminished.
But Van Uhm said Gaddafi was using civilians as human shields and hiding his armor in populated areas, curbing NATO's ability to hit targets. "The operational tempo remains, but we have seen a change of tactics (from Gaddafi)," he said. "When human beings are used as shields we don't engage."
There were other tactical changes.
"They are using more and more trucks and light vehicles ... and they are keeping more heavy equipment like armored vehicles (hidden)," said Van Uhm, who added that the end result was that Gaddafi was prevented from using heavy armor.
Diplomatic efforts to end the conflict in the oil producing nation have failed to make progress with the government side offering concessions, but insisting Gaddafi stay in power, and rebels adamant that Libya's leader for the past 41 years leave.
After a series of rapid rebel advances followed by headlong retreats, the insurgents held their ground for six days in Brega, putting their best trained forces in to battle for the oil town and keeping the disorganized volunteers away.
A sustained government bombardment of rockets and mortar bombs, however, pushed the insurgent pick-up truck cavalcade back toward the rebel stronghold of Benghazi, their biggest retreat in several days of inconclusive battles.
"Since the day NATO took over the air strikes, we have been falling back," said Ziad el Khafiefy, 20, a rebel fighter.
"Gaddafi's troops are hitting us with Grad missiles," said Mabrouk el Majbary, 35. "Something is wrong ... When the U.S. gave leadership to NATO, the bombings stopped."
The rebels had shown better organization than in past weeks, keeping territory for longer but government troops mounted a sustained assault on Tuesday.
The rebels are set for a boost with the arrival of a tanker in one of their ports which can carry one million barrels of crude, worth more than $100 million, which would be their first shipment since the fighting broke out.
A Turkish ship arrived at the port of Cesme in western Turkey on Tuesday afternoon carrying 321 injured Libyans after visiting Benghazi and Misrata. Sirens wailed as ambulances rushed the injured to nearby hospitals.
In the capital Tripoli, angered by fuel shortages and long queues for basic goods caused by sanctions and air strikes, some residents began openly predicting Gaddafi's imminent downfall.
Stepping up efforts to eradicate symbols of resistance against Gaddafi in western Libya, the army razed a mosque once used by rebels as a command center in Zawiyah. The government took reporters to the city to show it was under control.
"People are upset," said Mohammad, a shopowner. "How can you remove a mosque in a central square just like that? It's a Muslim country."
"Don't you see how tightly controlled we are now. Government spies have us surrounded in this city and we are scared to talk," said another resident. "Those were revolutionaries and civilians that they killed, they were not gangs or al Qaeda."
Stalemate on the frontline of fighting in eastern Libya, defections from Gaddafi's circle and the plight of civilians caught in fighting or facing food and fuel shortages prompted a flurry of diplomacy to find a solution to the civil war.
The government has offered concessions. Spokesman Mussa Ibrahim said Libya was ready for a "political solution" with world powers and offered a "constitution, election, anything. But the leader has to lead this forward."
Libyan Deputy Foreign Minister Abdelati Obeidi ended a diplomatic shuttle to Greece, Turkey and Malta to set out the government position. Libya's Foreign Minister Moussa Koussa, once a close ally of Gaddafi, has defected to Britain.
Turkey is expecting an envoy to visit from the opposition in the coming days and is listening to both sides.
"Both sides have a rigid stance," a Turkish Foreign Ministry official said after Obeidi's visit. "One side, the opposition, is insisting that Gaddafi should go. The other side is saying Gaddafi should stay. So there is no breakthrough yet."
There has been talk of Gaddafi staying on as an historic figurehead with one of his sons overseeing a change in Libya toward democracy. But many Western leaders see no role for Gaddafi in Libya's future.
"But let's be clear, when Gaddafi leaves, that is when the real difficulties start and we need to prepare for that, that is bringing the country together again," said Sweden's Foreign Minister Carl Bildt, who was involved in the Balkans conflict.
(Additional reporting by Alexander Dziadosz near Brega, Aaron Gray-Block in The Hague and Ibon Villelabeitia in Cairo, Justyna Pawlak in Brussels; Writing by Peter Millership; editing by David Stamp)
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