Greece must choose between reforming its economy or leaving the euro, Luxembourg's finance minister said Thursday, stressing that Athens faces tighter surveillance from the European Union.

Luc Frieden told reporters he was "relatively optimistic" eurozone finance ministers will take a decision on a stalled 230-billion-euro Greek rescue package on Monday but warned that more steps are needed in the coming weeks.

While the Greek coalition has met key conditions for a new bailout, he said a monitoring system must now be put in place and the Greek parliament must pass more measures by the end of February.

"The Greek authorities must implement these measures, but since taxpayer money from other (eurozone) states is involved, it is in a partnership that we must ensure that they are implemented," Frieden said, denying that this amounted to placing Athens under "wardenship."

"I don't agree that the Greeks do it on their own. We must do it with the Greeks, with an efficient surveillance system," he said, adding that Athens agrees.

Frieden warned that while the eurozone cannot kick a member out, Greece must reform in order to be in a condition to stay in the 17-nation eurozone.

"We all have an interest in keeping the eurozone intact, but we are not in a dictatorial monetary union.

"A state is free to choose to leave," he said.

"If a member state says, 'we prefer not to take money from other states and return to a national currency without making structural reforms,' then that state has chosen to exclude itself," Frieden said.

"It is therefore the responsibility of the Greek people to choose whether they want to stay in the eurozone."

Greece faces a March 20 deadline to repay 14.5 billion euros in debt or face a disastrous default.