Poland's top general resigned on Friday, the latest senior military figure to quit at a time when US and NATO troops are deploying in the country to reinforce the alliance's eastern flank.

The surprise resignations of several key generals over the last year have rocked Poland's right-wing government as it faces terse criticism at home and abroad over a host of controversial reforms.

"I am coming to the end of my duties as Chief of the General Staff of the Polish Armed Forces. On January 31, 2017 I will end professional military service and say goodbye to my uniform," General Mieczyslaw Gocul wrote in a statement published on the General Staff website.

Poland's PAP news agency said it was not immediately clear who would replace him but the role will fall to his deputy, General Michal Sikora, should no one be named by the end of January.

Rumours about Gocul's resignation began in December, after the departure of Lieutenant General Miroslaw Rozanski, who had reformed the chain of command and Brigadier General Adam Duda, who was responsible for arms purchases.

Rozanski's moves to put the army, air force, navy and special forces intended to give the General Staff strategic planning capacity were slammed by the governing Law and Justice (PiS) party.

Local media have speculated that the departures could be a protest against how PiS Defence Minister Antoni Macierewicz, who is on a crusade to stamp out all traces of the communist era, is running the military.

The generals quit amid heightened tensions with Poland's Soviet-era master Russia.

Last summer, NATO leaders endorsed plans to rotate troops into Poland and the three Baltic states to reassure them they would not be left in the lurch if Russia was tempted to repeat its Ukraine intervention.

The Pentagon has separately sent an armoured brigade with some 3,500 troops and heavy equipment to Poland.

This operation has sparked anger from Russia, with the Kremlin describing it as a "threat" on its "doorstep".

US President Donald Trump has suggested his administration will seek to ease tensions with Moscow, but a week into his presidency, the deployments remain intact.