By Erika Solomon and Douglas Hamilton
BEIRUT, March 28 (Reuters) - Syrian government forces kept up heavy weapons fire and siege tactics against opposition strongholds on Wednesday despite President Bashar al-Assad's acceptance of a peace plan calling for the army to withdraw to its barracks, activists said.
The Syrian Observatory for Human Rights reported military action against towns and villages from the southern province of Deraa to the Hama region 320 kms (200 miles) to the north.
Shelling was also reported in parts of Homs, Syria's third largest city, where Assad on Tuesday toured the devastated streets of a rebel bastion overrun by his troops earlier this month after weeks of bombardment.
"Military forces accompanied by dozens of armoured vehicles stormed the town of Qalaat al-Madiq and nearby villages (in Hama)," the activist website reported. "This comes after weeks of heavy gun and mortar fire and several failed attempts to invade the town."
"The regime has been shelling our town for 18 days, they are destroying our ancient fort," said one activist calling himself Abu Dhafer. "Thousands of people have fled and nearby villagers have gone to homes in safe areas. They are cramming people into their homes, a dozen to a room, men women and children."
"The rebels have left the town, it is surrounded and being shelled and we don't have enough weapons to fight back."
Syria has accepted a U.N.-sponsored peace plan calling for the withdrawal of troops and heavy weapons from cities ahead of peace talks between Assad and his opponents, special envoy Kofi Annan said on Tuesday.
The United States, Germany and other Western powers greeted the news with scepticism, saying they would wait and see what Assad actually did, rather than take his word for it.
"We will judge Assad's sincerity and seriousness by what he does, not by what he says," said U.S. Secretary of State Hillary Clinton, calling on him to order his forces to start withdrawing from populated areas.
Annan, who represents the United Nations and the Arab League, said getting Assad's agreement in principle to his six-point peace framework was an important first step but implementing it "is going to be a long difficult task."
Annan's plan calls for the withdrawal of heavy weapons and troops from population centres, for humanitarian assistance to be allowed in unimpeded, for the release of prisoners, freedom of movement and access for journalists to go in and out.
ATTACKS AT DAWN
Violent clashes between government troops and rebel ground forces began at dawn in Basr al-Harir in southern Deraa after security forces told residents to hand over the rebels or face an attack, the Observatory report said.
When the army tried to storm the town of Rastan in central Homs province in the early morning, three soldiers were killed and at least four rebels wounded. Mortar rounds exploded in the Old City of Homs, according to the activists' account.
Assad's opponents grouped around the Syrian National Council (SNC) remain sceptical of the Annan plan and Assad's proclaimed acceptance of its terms and continue to press for him to stand down.
"He is buying time. It means more killing. He is playing games," said SNC member Adib Shishakly. "Every hour we are losing five people. So really, time is life."
Russia, one of Syria's staunchest allies, meanwhile said it was sceptical of the "Friends of Syria" meeting due to take place in Istanbul on Sunday, saying it feared it would be a cloak for foreign interference.
"Such events, unfortunately, have a one-sided political direction," Russian Foreign Ministry spokesman Alexander Lukashevich said at a weekly briefing on Tuesday.
"The participants are not seeking to establish an inter-Syrian dialogue in the interest of ending the conflict but, on the contrary, are probably preparing the ground for interference from outside," he said.
Opposition unity talks that took place in Istanbul on Tuesday got off to an unpromising start when veteran dissident Haitham al-Maler and Kurdish delegates walked out, saying their views were not being heard.
Clinton urged Syria's fractious opposition to unite.
"They must be able to clearly demonstrate a commitment to including all Syrians and protecting the rights of all Syrians," she said. "We are going to be pushing them very hard to present such a vision in Istanbul."
"RETURN TO NORMAL"
Assad on Tuesday morning made a foray into the heartland of Syria's year-old uprising, visiting the devastated former rebel stronghold of Baba Amr in the city of Homs, which his forces overran after weeks of shelling. Syrian TV called it a "field inspection", and it appeared designed to show he could safely walk the streets.
"Life will return to normal in Baba Amr, better than it was before," Assad told a small crowd of supporters and soldiers.
Syrian state television on Wednesday showed children in the northern city of Idlib tripping gaily to school in complete safety. A little later, it was reporting on the "terrorist" menace stalking other parts of the country.
The United Nations estimates more than 9,000 people have been killed in Syria's upheaval over the past year. Syrian authorities blame foreign-backed terrorists for the violence and say 3,000 soldiers and police have been killed.
United Nations human rights chief Navi Pillay said on Wednesday she thought Assad bore direct responsibility for what his troops were doing.
"Factually there's enough evidence pointing to the fact that many of these acts are committed by the security forces [and that they] must have to seek the approval or the complicity at the highest level," she told the BBC.
"We also find that four sections of the security and military intelligence report directly to him. So this is the kind of things that judges hearings on crimes against humanity will be looking at, of command responsibility."
"The government says there are armed individuals in the civilian communities, that there are terrorists active. That is never an excuse to go and use heavy weaponry against civilians in densely populated areas. So under international law that is a crime."
She said she had also seen harrowing evidence that children were being mistreated in Syrian detention centres.
"It's just hoprrendous," she said. "Children shot in the knees, held together with adults in really inhumane conditions, denied medical treatment for their injuries, (and) either held as hostages or held as sources of information."
Assad's crackdown on the year-old uprising has angered Arab countries including former allies Qatar and Saudi Arabia, which favour arming the rebels. But Western and Arab governments which would be glad to see Assad ousted are wary of what might replace the 40-year-old family dynasty and its ruthless, but predictable, police state.