Portuguese Prime Minister Jose Socrates’ Socialists won elections with 36.56 per cent of the vote but failed to hold on to their absolute majority in parliament, official results showed.

The main centre-right opposition Social Democratic Party (PSD) captured 29.09 per cent of the vote, the interior ministry said.

The ministry also said that only the results of votes cast abroad were left to be counted.The result of the votes cast abroad, which select four seats in the Portugese Assembly, will be known on October 7.

They have traditionally been split between the Socialists and the PSD.

That will give the Socialists 96 seats in the 230-seat Assembly, down from the 121 they won in the last election in 2005.

The PSD will have 78 seats while the conservative Popular Party won 10.46 per cent of the vote, or 21 seats.

The far-left Left Bloc won 9.85 percent and 16 seats.

The Communist-Green Party coalition, the only other force to win representation in the Assembly, won 7.88 percent of the vote and 15 seats.

It is the first time that a government with an absolute majority has been returned to office for a second term with a minority in parliament, signalling possible political instability at a time of economic challenges.