Russian Foreign Minister Sergei Lavrov on Thursday demanded a detailed explanation from Washington and Warsaw for the deployment of US missiles near the Polish-Russian border.

Polish and US officials unveiled on Wednesday the first battery of US surface-to-air Patriot-type missiles to be stationed on Polish soil, at a base just 60 kilometres (40 miles) from Russia's Kaliningrad territory.

The move came despite a recent improvement in ties between Russia and the United States following the signing of a long-awaited nuclear arms reduction deal in April and a thaw with Poland after years of mistrust.

"We expect that some articulate explanations will be given," Lavrov told reporters.

"So far we're just told: 'Do not worry, this is not against you.' We have heard this," he said in televised remarks.

"We expect that the new nature of our ties with Washington and Warsaw allows us to count on more detailed explanations of what is happening."

Russian officials have said the deployment of the missiles jeopardizes stability in the region and does not help bilateral ties.

Poland says the deployment was aimed at upgrading its air defences and the site of the Patriot battery, a military base in the northeastern Polish town of Morag, was not chosen for political reasons.

Up to 150 US troops based in Kaiserslautern, Germany, are to service the battery in Poland and train Polish soldiers to operate it.