The German government said Tuesday that it was frustrated by the slow pace at which Russia was returning trophy art stolen by the Red Army during World War II. "No art is being repatriated at the moment and that will remain the case in the next few years," Wolfgang Maurus, the official responsible for trophy art under federal culture minister Christina Weiss, told reporters. Maurus said that about one million works of art and more than 4.5 million valuable books were spirited out of Germany to Russia during World War II. Weiss has described the negotiations with Russia as "extremely frustrating". "Friends should not treat each other this way and neither should contractual partners," Maurus said of relations between Berlin and Moscow, referring to a 1989 bilateral agreement on the return of trophy art. He said that German art experts had repeatedly been denied access to suspected storage sites in Russia.Officials for Berlin's Academy of Fine Arts told the news conference that nearly three-quarters of its renowned collection had disappeared without a trace include priceless draft designs for memorials for Martin Luther and Frederick the Great.