PRAGUE—The Czech Republic's three-party coalition government appeared to be heading toward collapse after a junior partner said it would quit.

The Liberal Democrats announced the move Thursday shortly after Prime Minister Petr Necas fired Karolina Peake from the post of defence minister, just eight days after she was appointed. Necas said the major reason for him to dismiss Peake was “clearly a loss of confidence.”

Peake chairs the centrist Liberal Democrats, the smallest member of the three-party coalition government. She said the party's leadership called on its ministers to resign from their government posts Jan. 10.

“Our ministers have been given a clear task to leave the government,” Peake said.

The coalition rules with the help of independent lawmakers, but its future without eight Liberal Democrats in Parliament looks uncertain.

Lubomir Zaoralek, deputy head of the major opposition Social Democrats called on Necas to resign. He said his party's leadership planned to discuss whether to ask for a parliamentary confidence vote in the government Friday.

The remaining two conservative parties, Necas' Civic Democrats and TOP 09, have only 90 lawmakers in the 200-seat lower house of Parliament.

Despite its weakness, the government pushed through the Parliament unpopular tax hikes on Wednesday that aim to bring the budget deficit below 3 per cent of GDP next year.

Peake was appointed Dec. 12 to replace Alexandr Vondra who resigned earlier this month. She angered President Vaclav Klaus and Necas when she immediately fired three senior ministry officials, including her first deputy Gen. Vlastimil Picek. Picek is a former Czech military chief of general staff who previously also served as the head of Klaus' military office.

Necas said he wanted the three to resume their posts again and decided to fire Peake after she refused to accept it.

“This is absolutely essential for me,” Necas said.

Picek is currently the chief negotiator for the Czechs with the Swedish side in ongoing talks to extend a lease on 14 JAS-39 Gripen fighter jets for the Czech air force.

Peake also appointed several controversial people at the ministry, including Ales Klepek as the head of her office. Klepek served in the same post under one of Peake's predecessors, Martin Bartak.

Bartak has been under police investigation since 2010 when former U.S. Ambassador William Cabaniss accused him of asking for money to solve a problem with a supplier that threatened a $150 million deal for Czech truck maker Tatra AS, where Cabaniss was chairman of the supervisory board.