Santana Lopes said he was proud of his cabinet

The move follows Friday's decision by President Jorge Sampaio to dissolve parliament and call early elections.

Mr Sampaio said that dissolving parliament was the only way to solve a crisis of credibility and instability.

The prime minister took office four months ago when Jose Manuel Barroso left the post to become president of the European Commission.

Their Social Democratic Party is currently trailing in the opinion polls behind the opposition Socialists.

Proud

"I informed the president of my and the government's decision, taken in the cabinet meeting just held," Mr Santana Lopes said on state television.

"We will undertake our responsibilities, but as a caretaker government," he said.

I am proud of my executive Pedro Santana Lopes Portuguese Prime Minister

"It would be bad if after last night's [Friday's] words from the president we kept the same posture and attitude," the prime minister said.

He was referring to President Sampaio's description of the work of the government that had forced him to call snap elections on 20 February.

"This government's negative succession of incidents and declarations, contradictions and disco-ordinations in whole led me to dissolve the parliament as the only solution for a grave crisis of credibility and instability," Mr Sampaio said on Friday.

The brief tenure of Mr Santa Lopes has been marked by the bitter resignation of a minister, slumping polls and allegations of government interference with the media.

But he told reporters on Saturday he would defend the honour of his cabinet colleagues.

"I am proud of my executive," he said.

The Socialists, under the new leader Jose Socrates, are believed to have a good chance of winning the February election.