The Pheu Thai Party declared on Thursday that the National Council for Peace and Order and its government have lost all legitimacy to remain in office.
It accused them of limiting freedom, intending to prolong their hold on power and placing their own people in supposedly independent organisations.
The biggest political party's statement said the practices of the NCPO and the government prevented them solving national and public problems, and would lead to national crises in the future.
Accusing them of trying to cling to power, Pheu Thai said the NCPO would appoint senators who would be its political base. It also referred to changes to the electoral system, the new law on political parties, and the exercise of Section 44 of the interim constitution to weaken old political parties.
Pheu Thai accused the government of threatening pro-democracy activists and failing to develop national reconciliation and tackle corruption.
It also criticised Prime Minister Prayut Chan-o-cha for failing to organise a general election organised no later than November this year, as earlier announced.
