Donald Tusk, leader of Poland's main opposition party, the centrist Civic Platform (PO), is under the protection of the State Security Service after police reported a possible threat.
Polish opposition politicians have criticised ideas presented at a congress of the ruling party, the conservative Law and Justice (PiS), saying it was a failed attempt to revive enthusiasm among the party's "fat cats."
The Civic Coalition (KO), Poland's main opposition grouping, will make an attempt to block the president-signed 60 percent pay rise for parliamentarians, the KO spokesman has said.
Donald Tusk, the former prime minister, has announced his return to Polish politics with a stinging attack on the governing Law and Justice party and its leader Jarosław Kaczyński.
Poland's main opposition party has urged President Andrzej Duda to clear up doubts related to the financing of his presidential campaign last summer.