By Marcin Goclowski and Lidia Kelly
WARSAW (Reuters) - Mateusz Morawiecki was sworn in as Poland's new prime minister on Monday and European Council President Donald Tusk called on the new leader to pursue European unity.
Poland's ruling Law and Justice Party (PiS) is at odds with the EU over immigration, logging in an ancient forest and government attempts to control the courts and the media. Critics say the eurosceptic party's policies have subverted democracy and the rule of law.
At the same time, acrimony between Tusk and the PiS dates back years. Poland, acting on orders from the PiS boss and long-time Tusk adversary Jaroslaw Kaczynski, was the sole member of the 28 EU members to vote in March against Tusk's re-election.
Morawiecki, 49, replaced Beata Szydlo, who became a deputy prime minister. PiS sacked the popular Szydlo last week in a bid to improve Poland's image abroad and prepare the conservatives for a series of elections.
Morawiecki will remain finance minister and economy minister. All other ministers have kept their jobs for now, although some ministerial changes are expected in weeks to come.
Morawiecki said his government will continue the work of Szydlo. He is expected to outline his policies on Tuesday.
Tusk, a former Polish prime minister before PiS came to power in 2015, said he counts on good cooperation.
"Acting for Poland's strong position in the European Union and for the unity of all member states is the need of the moment," Tusk wrote.
Former Polish President Lech Walesa, who is a critic of the PiS said on Twitter: "The circus has stayed the same, only the clowns have changed their roles." Walesa led protests and strikes that shook communist rule in the 1980s.
Szydlo's government was one of the most popular in Poland since the 1989 collapse of communism. It registered around 40 percent approval due to low unemployment, increases in public spending and a focus on traditional Catholic values in public life.
(Reporting by Marcin Goclowski and Justyna Pawlak, writing by Lidia Kelly; Editing by Matthew Mpoke Bigg)