Jakarta – The Prosperous Justice Party (PKS) has proven itself to be a party of trouble makers by threatening to disclose a political contract it signed with President Susilo Bambang Yudhoyono before joining the government coalition, says a Democratic Party official.

PKS secretary-general Anis Matta recently said that the party would reveal clauses of the contract if the President replaced PKS ministers in an upcoming reshuffle of the presidential Cabinet.

"The PKS has violated statehood norms; reshuffling the Cabinet is the President's prerogative. The threat impedes the President's work for the people," Democratic Party deputy chairman Pasek Suardika said Tuesday in Jakarta.

He said this was not the first time the PKS had caused problems in the coalition, adding that it had been more troublesome than the other coalition members.

"We're annoyed. The PKS needs to learn how to communicate; and how [to differentiate] between coalition members and opponents. It shouldn't wear a coalition costume if on the inside it is the opposition," Pasek said, as quoted by Antara news agency.

He added that Yudhoyono was currently appraising the PKS ministers' "grade point average", and that the PKS had made the threat because it worried about its ministers' performances.