Poland's president will on Monday swear in members of a government that will likely only last until December, in what opposition parties say is a "farce" intended to delay them from taking power after they won a majority in an October election.

The nationalist Law and Justice (PiS) party, in power since 2015, came first in the election but fell well short of the 231 seats needed for a majority and appears unlikely to win a vote of confidence in parliament.

A broad alliance of Pro-European Union parties secured 248 seats and declared their readiness to form a government, but nevertheless PiS ally President Andrzej Duda gave Prime Minister Mateusz Morawiecki the first shot at doing so.

Prominent PiS politicians Mariusz Blaszczak and Jacek Sasin have said they will not join the new government, leading opposition politicians and commentators to say that the party's big-hitters do not want to join an administration that is doomed to failure.

However, in an interview published on Monday, PiS leader Jaroslaw Kaczynski said the suggestion that the party's heavyweights did not want to participate was "an outright lie" and that forming a government made up of experts rather than politicians had been his idea.

"The point is that there should not be too many politicians in this government," he told state-run news agency PAP. "We want to show that it is possible to govern differently."

The prime minister has vowed to implement the policy proposals of opposition parties in a bid to persuade them to work with him.

However, his appeals have gained little traction with lawmakers who accuse PiS of presiding over democratic backsliding that has blocked European Union funds, an erosion of women's rights, the demonisation of minority groups like the LGBT community and rampant nepotism in state companies.

Opposition parties accuse the government of stalling tactics designed to cover up evidence of wrongdoing during their time in power.

"We all know that this is one big comedy and farce," Marcin Kierwinski, a lawmaker from the liberal Civic Coalition (KO) grouping told private broadcaster Radio Zet. "It is a fight for time." (Reporting by Alan Charlish and Pawel Florkiewicz, editing by Ed Osmond)