Donald Tusk, Poland's PM, in hospital with infection

WARSAW, Jan 24 (Reuters) - Poland's Prime Minister Donald Tusk was hospitalised on Wednesday due to a severe infection of his respiratory system, his office said in a statement.

Tusk, Poland's longest serving prime minister who has been in office since 2007, will nonetheless go to parliament on Thursday for a vote of no confidence against his health minister, but then will return to hospital.

"The doctors will decide in this matter. The prime minister is under very good care and should quickly return," government spokesman Pawel Gras told reporters. "This is an important vote."

Tusk's centre-right coalition has 235 seats in the 460 seat lower chamber of the parliament and has never lost a no-confidence vote against its ministers, so his presence will be symbolic rather than necessary to defeat the motion.

Tusk's Civic Platform maintains a wide lead in the polls over the main rightist opposition Law and Justice party, even though the country's economy has seen a significant slowdown in recent months.

Law and Justice is seeking to boot out Health Minister Bartosz Arlukowicz, accusing him of failing to deal with what they say is the awful state of the health care system.

(Reporting by Chris Borowski and Marcin Goclowski; Editing by Alison Williams)