MOSCOW (AP) - An aide to Russian President Vladimir Putin has handed the United States additional information to back Moscow's efforts to get Washington to designate some Chechen militant groups as international terrorist organizations, the Interfax news agency reported Thursday. Sergei Yastrzhembsky, Putin's top spokesman on Chechnya, presented the evidence to U.S. officials during a visit to Washington, Interfax reported. It said Yastrzhembsky said the United States was prepared to put the groups on the State Department list of terrorist organizations. "We see willingness on the part of our colleagues and partners from the United States to continue and complete this work," the agency quoted Yastrzhembsky as saying in Washington. "The work has progressed very far, but it takes time to thoroughly examine all the materials," he said. In Moscow earlier this month, U.S. Deputy Secretary of State Richard Armitage said the United States was working "very closely" with Russia "about the process of designating some Chechen terrorist groups as foreign terrorist organizations." Russia claims that international terrorists are deeply involved in supporting Chechen separatists who have been at war with Russia since 1999, the second conflict in the mostly Muslim region in a decade. The Kremlin has in part justified its harsh crackdown in Chechnya as part of the international anti-terror campaign and would very much like to have its view vindicated by putting Chechens on the U.S. list of international terrorist organizations. Officials have not publicly identified any specific groups under discussion.