president Anibal Cavaco Silva got 52.9 per cent of the votes [AFP]

Portuguese President Anibal Cavaco Silva has won a second term, promising to work for political stability as the government fights to avoid an international bailout.

Cavaco Silva, 71, an economist and member of the opposition Social Democratic Party, got 52.9 per cent of the votes, according to near final results released late on Sunday.

His main rival, socialist Manuel Alegre, won 19.7 per cent of the ballot, in an election that was marked by a turnout of less than 47 per cent following a low-key campaign.

"The immediate priorities are the fight against the scourge of unemployment, the reduction of external debt and the reinforcement of economic competitiveness," the president said.

"I will be a frame of reference of confidence, stability and solidarity," he said.

"The task we have before us is big and very demanding."

Some 9.6 million voters were eligible to choose from among six candidates.

There is growing concern about rising unemployment pegged at 11 per cent and poverty as Lisbon implements its third austerity plan in a year.

"I believe it's very important for Portugal to have political stability to resolve its problems," Cavaco Silva said shortly after casting his vote.

Though it carries great moral authority, the Portuguese presidency has limited executive power, though the president can dissolve parliament.

Since the end of Portugal's dictatorship in 1974, all incumbent presidents standing for a second term have been re-elected.