Top eurozone official Jean-Claude Juncker is insisting that parties supporting Greece's coalition government must sign commitments to honour a new financial rescue deal after the next general election, or the agreement could be frozen.

Juncker told the German business newspaper Handelsblatt, in an interview published today: "The government has three political parties and they all need to sign the agreement."

Juncker, who is Luxembourg's prime minister and chairman of the Euro-Group, issued the warning amid growing EU concern that Greek political parties are abandoning their consensus they the general election, expected in late April, draws closer.

As EU-IMF envoys continue their latest inspection in Athens, Juncker said Athens needed to speed up reforms aimed as achieving long-term savings.

"The government is under pressure - that's true. But the structural reforms are progressing too slowly ... This casts a shadow on Greece."