Kazimierz Marcinkiewicz' choice is thought to speed up coalition talks

The Law and Justice (PiS) party was widely expected to choose its own leader, Jaroslaw Kaczynski.

But Mr Kaczynski said Kazimierz Marcinkiewicz, 45, was the best choice if the party wanted to "quickly create an effective government".

The announcement was welcomed by the PiS' allies, the Civic Platform (PO).

"Kazimierz Marcinkiewicz is well-prepared to deal with economic issues, which were a source of dispute between us and the Civic Platform," Mr Kaczynski said.

"This dispute must be settled."

The PO, which came second in the election and is the PiS' future government partner, is a pro-business party.

The socially conservative PiS is more welfare-oriented, and Mr Marcinkiewicz has already announced that compromises on the new government's economic policies will be necessary.

Talks to form the new government are expected to start this week.

The two parties have different views on taxes and free market reforms, but agree that stamping out corruption must be their top priority.

Surprise move

The PO's leader, Donald Tusk, later voiced his surprise at the choice of premier, but added that his party accepted the decision.

The choice of Mr Marcinkiewicz might have been prompted by the fact that Mr Kaczynski's identical twin brother Lech, a former justice minister who cracked down on crime, is running for president in next month's vote.

The PiS' leader had already pledged not to accept the role of prime minister if his brother was elected.

Mr Marcinkiewicz, a former physics teacher, is the head of the parliament's treasury commission.

His economic competence is widely acknowledged.

Polish President Aleksander Kwasniewski has to approve his candidacy before it becomes official.

Sunday's turnout was only 40% - six percentage points lower than at the last election in 2001.

The PiS won 26.99% of the vote, followed by the PO with 24.14%.

The former ruling Democratic Left Alliance, which won 41% of the vote in the previous parliamentary elections four years ago, secured a meagre 11.31% this time.