Portugal's Prime Minister Antonio Costa tested positive for coronavirus on Tuesday, his cabinet said, as he prepared to govern solo just days after scoring a parliamentary majority.

"He does not have any symptoms and will respect an isolation period of seven days," it said.

The news comes after the premier's Socialist party won 117 seats in the 230-seat parliament in Sunday's snap election.

Costa, who has headed two minority governments since 2015, was expected to meet President Marcelo Rebelo de Sousa on Wednesday.

The head of state, who started talking to lawmakers from all sides about the new cabinet on Tuesday, had been expected to formally invite Costa to form a fresh government.

The line-up is not expected to be unveiled until the last week of February after the new parliament starts work, the cabinet has said.

Costa has never announced having Covid-19 before, though he has had to isolate before, including after coming into contact with France's President Emmanuel Macron who tested positive in late 2020.