Germany's parliament approved an extension of Greece's bailout on Friday after Finance Minister Wolfgang Schaeuble, who has voiced doubts about whether Athens can be trusted, promised he would not let Greece "blackmail" its euro zone partners.

With 542 members of the Bundestag voting "yes", including almost all of Chancellor Angela Merkel's right-left coalition and the opposition Greens, it was the biggest majority so far for a euro zone rescue package. There were 32 "no" votes and 13 abstentions.

The Bundestag vote was the only major parliamentary hurdle for a four-month extension to the bailout programme for the most heavily indebted country in Europe's single currency zone.

Schaeuble urged lawmakers to take what he acknowledged was a difficult decision, appealing to their sense of responsibility.

"We Germans should do everything to keep Europe together as far as we can and bring it together again and again," said 72-year-old Schaeuble, who makes no secret of his doubts about how far Greece's leftist Prime Minister Alexis Tsipras and Finance Minister Yanis Varoufakis can be trusted to deliver on reforms.

Addressing public misgivings in Germany about making further concessions to Greece - whipped up by top-selling daily Bild's front-page campaign for lawmakers to say "NEIN!" - Schaeuble said no new financial aid was at stake.

"We're not talking about new billions for Greece, we're not talking about any changes to this programme - rather it's about providing or granting extra time to successfully end this programme," he said, adding that solidarity among members of the single currency "doesn't mean you can blackmail each other".

The debate reflected widespread misgivings about granting the Greeks more time, with one poll this week showing that only 21 percent of Germans back an extension for Greece.

"Look at Tsipras, look at Varoufakis: would you buy a used car from them?" asked Klaus-Peter Wilsch, one of a small group of dissidents from Merkel's Christian Democrats (CDU).

The CDU's Bavarian sister party, the CSU, said Athens was being given a "last chance" to get its economic act together.

Germany's ruling conservatives do not disguise their dislike of what their parliamentary leader Volker Kauder has called the "loutish" behaviour of the Greek government. Schaeuble has told lawmakers in private that Varoufakis' remarks reviving talk of a debt "haircut" had strained EU solidarity with Greece.

While Merkel and Schaeuble's tough stance on Greece goes down well with German voters, the euro zone crisis has created space for a new Eurosceptic party to the right of the CDU/CSU - the fast-growing Alternative for Germany (AfD).

AfD leader Bernd Lucke wants Greece kicked out of euro and said extending the bailout was "a bad decision for Germany and for Greece ... because economic misery in Greece will continue".

But the European Commission's financial affairs chief Pierre Moscovici reminded Berlin in an interview with German radio just before the debate that allowing any country to exit the euro zone would merely raise the question "who is leaving next?".