MOSCOW, June 20 (RIA Novosti) - Russia's foreign minister said on Friday that talks with the United States over its missile shield plans for Central Europe have stalled.

Moscow has strongly opposed the possible deployment by the U.S. of 10 interceptor missiles in Poland and a radar in the Czech Republic as a threat to its security and nuclear deterrence. Washington says the defenses are needed to deter possible strikes from "rogue states."

"Dialogue has stalled," Sergei Lavrov said. "Every new meeting indicates that the proposals being made [to allay Russian fears] are shrinking and becoming less convincing."

Lavrov said only concrete and transparent steps by Washington could soften Russia's stance toward the European missile shield.

During their visit to Moscow in late March, U.S. Defense Secretary Robert Gates and Secretary of State Condoleezza Rice offered to let Russia monitor the proposed U.S. missile and radar bases in Eastern Europe.

Washington has also offered not to activate the system until there is a "clear and present" threat from Iran or other potential adversaries.

"Nothing has changed since then," Lavrov reiterated on Friday.

He also said Russia had not received any official confirmation that the United States and Lithuania were formally discussing deploying elements of the U.S. missile shield in the ex-Soviet Baltic state if talks with Poland failed.

Poland has taken a tough stance in the missile talks with the U.S., demanding it upgrade its air defense systems as a condition for agreeing to station 10 interceptor missiles on its territory.

Poland's deputy foreign minister and chief negotiator said on Tuesday that Washington and Vilnius were holding missile defense talks. "Lithuania's defense minister proposed it himself in May and the Polish side knows it," Witold Waszczykowski said.

The U.S and Lithuania both denied the report.

"It is difficult to comment on this statement because all we know about the talks [between the U.S. and Lithuania] is what the media reported," Lavrov said.

"The whole media frenzy around the [U.S.] missile shield clearly demonstrates how many additional factors there are," he added.