The first-ever battery of US Patriot missiles to be deployed in Poland will arrive in late May, defence ministry spokesman Janusz Sejmej told AFP on Wednesday.

"Following preparations and consultations, the first deployment of a battery of anti-missile Patriots will start around May 24 in Morag," Sejmej said.

The Polish military base at Morag, in the Mazurian Lakes region, is some 250 kilometres (150 miles) north of Warsaw and just 60 kilometres (40 kilometres) from the border with Russia's Kaliningrad territory.

Sejmej refused to say how long the deployment would last, but said it was "temporary".

In February, Poland ratified a deal on the stationing on its soil of US troops who will crew the surface-to-air Patriot battery. They are also due to train Polish soldiers to use the system.

Poland has repeatedly insisted that the base close to Kaliningrad was not chosen for political or strategic reasons, but simply because it already has good infrastructure.

In September 2009 US President Barack Obama scrapped a plan agreed a year earlier by his predecessor George W. Bush to install a controversial anti-missile shield system in Poland and the Czech Republic.

Under that now-shelved deal, the United States also pledged to help upgrade Poland's national air defences with Patriot missiles and has stuck to that part of the agreement.

The anti-missile shield plan had enraged Russia, which dubbed it a menace to its security on its doorstep, although Washington insisted it was meant to ward off a potential long-range missile threat from Iran.

Warsaw and Prague were part of Moscow's Soviet-era sphere of control, but became solid US allies after breaking from the crumbling communist bloc in 1989, and joined NATO in 1999.

The Obama administration has since come up with a new plan aimed at parrying short- and medium-range missile attacks.