The leader of Spain's anti-austerity party on Sunday hailed a clear election victory by its Greek radical left-wing ally Syriza, saying it would free Greece from austerity politics which he said were dictated by Germany.

"The Greeks are going to have a true Greek president and not a delegate of German Chancellor Angela Merkel, (a president) who will put the interests of his country and his people first," Podemos leader Pablo Iglesias told Spanish private channel Sexta in an interview.

"We will work to support Syriza but we will also work in Spain, acknowledging that it is a different economic and political reality," said Iglesias, who visited Athens for Syriza leader Alexis Tsipras's final campaign meeting.

Stressing the relative importance of Spain's economy, the fourth biggest in the eurozone, he added: "We are not threatened by the Bundesbank (Germany's central bank) and 2015 will be the year of change."

With most of the votes counted, results showed Syriza won 149 seats in the 300-seat Greek parliament, just two short of an absolute majority.

Like Syriza, Podemos has found considerable popular support by rejecting austerity programmes adopted to try to lift the countries out of deep economic crisis.

"Hope is coming, fear is fleeing. Syriza, Podemos, we will win," Iglesias said earlier, shortly before exit polls were issued in Greece showing Syriza leading Sunday's vote.

"In Greece tonight, we are already hearing that. We are hoping we will hear the same thing in Spain soon," he told a gathering of about 8,000 party faithful in the eastern city of Valencia.

Greece's conservative New Democracy party of Prime Minister Antonis Samaras, the former party of government, was routed and reduced to around 76 seats.

Spain's conservative Prime Minister Mariano Rajoy earlier Sunday warned austerity-weary voters against the temptation to back Podemos in elections due this year.

He said that hard-won economic recovery must not be lost by a voter "leap in the dark".

"We can not bet our future and that of our children in a frivolous game of Russian roulette," Rajoy told a congress of his Popular Party in Madrid.