Portugal's Parliamentary Affairs Minister Miguel Relvas has resigned in a new sign of political unease before an important court decision.

The reason for the resignation was not immediately given.

Mr Relvas, one of the most unpopular figures in the cabinet, has long faced allegations that he obtained his university degree without completing the required course credits.

Expresso weekly newspaper said on its web site that an investigation by the education ministry into Mr Relvas's degree had accelerated his decision to step down.

He quit a day after the government easily defeated a no-confidence motion brought by the opposition Socialists in parliament over Portugal's austerity policies under an EU/IMF bailout.

Although defeated, the motion united all the opposition in parliament against the austerity drive, adding to concerns the government's budget-tightening measures required by the bailout may suffer defeat in the Constitutional Court.