Belgian Prime Minister Charles Michel might encounter trouble next week in keeping his government in place after the biggest party in his coalition quit on Saturday after a disagreement over signing the UN migration pact.

The Flemish N-VA said they were pulling its ministers from the coalition because Michel would be signing the UN migration plan in Marrakesh, Morocco, on Monday, despite their objection to it.

N-VA’s leader Bart de Wever had issued an ultimatum to Michel saying he would quit the government if he signed the non-binding UN declaration.

Michel said he would continue with a minority administration and would reshuffle posts — a difficult task for the government since French and Dutch speakers must have an equal number of ministerial posts by law.

The Belgian prime minister said he would maintain a minority coalition with French-speaking liberal Reformist Movement (Mouvement Reformateur) and two Flemish parties, the centre-right CD&V and Open VLD.

"A word is a word. That is why I will defend Belgium at the international conference of the United Nations. The orange-blue government focuses on continuity, responsibility and stability," said Michel in a tweet.

Other European states — particularly from Eastern Europe — will not be signing the migration pact because they fear it could increase immigration to Europe.