Greek Prime Minister Alexis Tsipras on Sunday said he would call a confidence vote in his government after his coalition ally quit, leaving him bereft of a parliamentary majority and raising the possibility of snap elections.

Earlier, Greece's right-wing defense minister resigned in protest at a deal ending a long running dispute with Macedonia over its name, saying he was taking his other six ministers in cabinet with him.

Panos Kammenos's Independent Greeks party had seven MPs, enough to get Tsipras's administration past the threshold of 150 deputies in the 300-member parliament. Tsipras's Syriza party has 145 seats and also the support of one independent lawmaker.

"I have taken my decision and have informed the president of parliament that we will immediately move to the process outlined by the constitution for the renewal of the confidence in my government," Tsipras told journalists.

The confidence vote is expected to take place later this week. Kammenos said he would not support Tsipras in the vote.

Syriza is trailing between eight and 12 points behind the main conservative New Democracy party, which also opposed the deal with Macedonia, in pre-election polls.

A firebrand leftist, Tsipras was elected in 2015 on a platform of anti-austerity but was forced into a third international bailout to bring back Greece from the brink of bankruptcy. The country exited a bailout program in mid-2018.