WASHINGTON (AFP) - The United States (US) has voiced its concerns to Russia over plans to move nuclear-capable missiles close to the borders of neighbouring states, a US official said on Monday.

"We've urged Russia to take no steps to destabilise the region," State Department deputy spokeswoman Marie Harf said, adding the US had also passed on to Moscow its neighbours' concerns at the plans to deploy Iskander-M missiles in the Kaliningrad area.

Poland and three Baltic states on Monday also expressed alarm that the missiles would be close to their borders.

"We certainly know the countries in the neighbourhood have expressed concerns over it, and we'll keep talking to them about it," Ms Harf said.

The Russian deployment comes in response to the planned US-led deployment of a disputed air defence shield, which Washington has long argued is not aimed at Moscow.

The advanced version of the Russian missile has a range of 500 kilometres and could potentially be used to take out ground-based radar and interceptors of the new Nato shield.