The Wall Street Journal reported that the $260 million facility will be located in Powidz, some 200 km (120 miles) west of Warsaw, and will house armoured vehicles, ammunition and weapons for a brigade.

Building work will start later this year and is expected to take two years, alliance chief Jens Stoltenberg told the Journal. A NATO official confirmed the report was accurate.

NATO has increased defences along its eastern flank in the wake of Russia's annexation of Crimea and its role in the ongoing Ukraine conflict.

Battlegroups have been deployed in the three Baltic states as well as Poland and NATO has launched an overhaul of its command structure and is taking steps to improve how quickly it can move troops and equipment around Europe in case of incursion.

The practice of "pre-positioning" equipment in strategic locations is also aimed at making it easier to deploy resources quickly in a crisis.

Stoltenberg told the Journal the new facility would "underpin the increased US presence in Poland".

Poland's government has been beefing up its military ties with the US, last month agreeing to buy American mobile rocket launchers worth $414 million and a year ago signing a $4.75 billion contract for a US-made Patriot anti-missile system.

Warsaw has also been pushing for the US to open a permanent military base. Nearly 5,000 American troops are already stationed on a rotational basis as part of NATO operations.