EU Commission President Jean-Claude Juncker says he looks forward to working with Syriza leader Alexis Tsipras for "the benefit of the citizens of Greece and the European Union".

In an open letter, external, he adds: "Promoting sustainable jobs and growth, while ensuring fiscal responsibility, is a common challenge across the European Union. The European Commission stands ready to continue assisting Greece in achieving these goals."

Agustin Rossi tweets, external: My 2 cents on #greeceElections Winning the elections was the easy part. 2) Sometimes, the revolutionary thing is making unthinkable reforms

German Foreign Office

tweets, external: FM #Steinmeier on #GreeceElections: We offer cooperation, but we hope+expect that #Greece honors the commitments she set herself.

Andrew from Greece emails: I'm 19 years old. To begin with, even though spirits are high, due to Syriza's win, uncertainty is still here. Good thing is that a proper government was created today, which means that we will not go to second elections. People are also afraid for their money, because banks run out of money. Young people are the main supporters of Syriza, but unfortunately there is a big percentage who supports Golden Dawn. Last but not least, I would like to make certain that we still believe in our European allies, that we together make plans for our recovery.

Spanish Prime Minister Mariano Rajoy has congratulated Alexis Tsipras and said he hoped he would form a "stable" government.

"I wish to congratulate you for Syriza's victory," he said. "I hope the election result leads to the forming of a stable government committed to the programme of European integration that Greece and Spain share."

Gabriele Steinhauser, The Wall Street Journal, Brussels

tweets:, external One thing Greeks are definitely much faster at than Germans: building a coalition government. #competitiveness

Ian Catterall in Plymouth emails: After living in Greece for some time with my partner, I can only congratulate the people of that country for their courage over the past few years. I hope that their future government will bring them hope.

At least one German newspaper seen by BBC Monitoring is wondering if Syriza leader Alexis Tsipras might have to execute a drastic U-turn after the election.

A lead article by Christiane Schloetzer in Sueddeutsche Zeitung says: "Right until the end, Tsipras cultivated his image as a rebel. However, many of his compatriots now believe that the left-wing politician will follow his brilliant victory with what the Greeks call a 'kolotumba' - a somersault."

The German Embassy in London

tweets, external: ‏Amb #Ammon: friendship & good relationship with #Greece are important. Goal of our work is to stabilise the whole eurozone, including Greece

Don't miss our 45-second video profile of Alexis Tsipras, the young, charismatic leader of Syriza.

The BBC's Jasmine Coleman in Athens describes how the night unfolded for Syriza party supporters: Syriza joy after Greek poll victory

Manfred Weber, leader of the European People's Party in the European Parliament

tweets, external: Reform path in #Greece needs to be continued. Soon it will become clear that Mr Tsipras makes empty promises @EPPGroup

Turkey's Foreign Minister Mevlut Cavusoglu says that his country is "ready to work with any government elected to power" and that the decision of the Greek people should be respected, Turkish newspaper Today's Zaman reports.

UK opposition leader Ed Miliband says that the British government should not "play politics" and should instead work with the new Greek government.

"Just like our elections are a matter for the people of this country, who the Greek people elect is a decision for them."

Axiomatic Goose tweets, external: @bbc_haveyoursay years after bailout Greeks see persisting stagnation, corruption & misery. It isn't surprising they want renegotiation.

Nick Childs
World affairs correspondent, BBC News

Greece and Europe have woken up to a political earthquake and are busy digesting the potential consequences. It's a dramatic change of the political guard in Greece.

As German newspapers record Greece's dramatic shift to the left, German and EU leaders will be bracing for what will be difficult negotiations, and no doubt more turbulent times for the eurozone.

After the celebrations of the night before, they are clearing up outside Greece's parliament. Many Greeks may see the dawn of a new hope, but many others still question what the price will be, in Greece, and beyond.

With the election over, a worker dismantles the Syriza party's election kiosk in Athens. The slogan reads: "Hope is on its way."

Image source, Reuters

Gabriel Gatehouse, BBC News

tweets:, external Just asked Russian ambassador if Russia wld provide assistance to Greece if talks with EU/IMF break down. "That's a matter of negotiation."

UK Prime Minister David Cameron's spokeswoman says he "respects the decision of the Greek people" but adds: "Greece needs to deal with its deficit and meet its international commitments."

Derek Gatopoulos, AP journalist

tweets, external: Tsipras to take secular oath. New Democracy says he's wrong to ignore tradition