The Texas Democrat, who has served in Congress since 2005, has said he will cooperate with “any investigation."
The pact calls for territorial concessions and the deployment of nearly 2,000 Russian peacekeepers to the area where full-scale fighting began Sept. 27.
The practice is "arbitrary and violates international law," the spokesman said.
Lawyers for some of those arrested said their clients had been subjected to beatings, verbal abuse and forced medical examinations.
Trump's Indonesian business partner is just the latest to come under investigation.