Russian First Deputy Prime Minister Sergei Ivanov on Thursday shrugged off possible cooperation with the United States on its missile defense system.

"As for possible cooperation in strategic anti-missile defense, honestly speaking, I see no reasons for that," Ivanov, who served as defense minister before being promoted, told reporters in the Ural mountains city of Yekaterinburg, the Interfax news agency reported.

"We believe this strategic anti-missile defense system is somewhat chimerical, to put it mildly," he was quoted as saying.

He however said U.S. plans to build missile defense sites in eastern Europe may be discussed during a visit by U.S. Defense Secretary Robert Gates, who is scheduled to arrive in Moscow next week.

Ivanov reiterated Moscow's concern over the U.S. missile defense plans. "We do not understand why this system is necessary in eastern Europe -- Poland and the Czech Republic," he said.

The United States is negotiating with Poland and the Czech Republic for the deployment of interceptor missiles and a radar tracking system in the two countries respectively.

Washington says the system would be able to help most of its European allies fend off long-range missile attacks, while Moscow has sharply criticized such plans.