Russia on Tuesday accused the United States of stepping up plans to install an anti-missile system in Europe, according to Interfax news agency.

The comments from Russian Deputy Foreign Minister Sergei Ryabkov mark a sharper tone from Moscow after a series of conciliatory comments on U.S. plans to deploy elements of the system in Central Europe.

Moscow said it had hoped the administration of U.S. President Barack Obama would revise plans initiated under former President George W. Bush to construct the system and welcomed calls initiated by the U.S. side to "reset" relations.

"The U.S. has not revised its plans. I do not think that this could happen. On the contrary, we can see that work in missile defense has intensified, including in the NATO format," Ryabkov was quoted by Interfax as saying.

Washington says deployment of interceptor missiles to Poland and a radar system in the Czech Republic does not target Russia, but future potential attacks from countries like Iran.

The new U.S. administration has been less assertive in pushing the plan, insisting it would be reviewed for cost-effectiveness and viability, although Obama stood by the overall scheme during a speech in Prague earlier this month.

Ryabkov repeated Moscow''s threat that if the United States does go ahead with the anti-missile system, that Russia will respond by placing its short-range Iskander missiles in the Kaliningrad enclave, nestled between NATO members Poland and Lithuania.