Warsaw: Poland will join the fight against Islamic State, its defence minister said on Wednesday, though he signalled that the scale of its involvement would depend on NATO's response to Russia's renewed assertiveness on the alliance's eastern flank.

The announcement, made by Defence Minister Antoni Macierewicz​ after a meeting with US Defence Secretary Ash Carter in Brussels, confirmed an earlier Reuters report that Poland would boost its Middle East involvement in an attempt to convince its allies to shift NATO forces eastwards.

Polish soldiers in Babylon, Iraq, in 2003. Polish troops are again on their way to the Middle East to join the fight against Islamic State. Credit:AP

"Poland has joined the actions, which are now so crucial, on NATO's southern flank," Mr Macierewicz told reporters.

"When it comes to details ... we will continue to discuss it, particularly as we consider it in the broad context of NATO's situation, hoping that both the US and NATO as a whole will back Poland and other countries on the eastern flank with their ... permanent presence."