Hundreds of Soviet KGB spies are operating in Berlin, but German authorities are reluctant to arrest them because of improved ties with the Soviet Union, a newspaper reported Friday.

The Berliner Morgenpost said at least 400 KGB agents were still operating in Berlin. The paper said its information came from former East German secret police agents.The Nov. 5 arrest of a KGB major in Potsdam was a "warning signal" to the Soviets, the paper said.

German officials hope the Soviets will withdraw their spies on their own initiative, the paper said.