Greek Prime Minister Alexis Tsipras has begun talks with one of his country's main creditors, as the EU awaits a clear signal from the new government on how it plans to pay off its massive debt burden.

Tsipras was welcomed Wednesday at the European Commission, one of the three main institutions supervising Greece's finances, by President Jean-Claude Juncker.

The two grabbed each other's hands and swung them merrily as they walked to their meeting without talking to reporters.

On the eve of their talks in Brussels, Juncker underlined that the EU would show flexibility helping Greece to deal with hundreds of billions of euros in foreign debts, but ruled out wholesale policy changes.

Tspiras is due later to hold talks with European Council President Donald Tusk, before heading to France.