Belgian Prime Minister Yves Leterme has tendered his government's resignation to the king after failing to carry out political reforms.
Mr Leterme had set a 15 July deadline to push through measures to devolve more power to the regions.
He took office in March - after nine months of political deadlock - as the head of a coalition of Dutch and French-speaking parties.
King Albert II has yet to decide whether to accept the resignation.
The government coalition includes Mr Leterme's Flemish Christian Democrats from the north as well as Socialists from the French-speaking region of Wallonia in the south.
The prime minister was due to present a state reform deal in a speech to parliament on Tuesday.
Before last June's general election, Mr Leterme had promised his supporters even more devolved powers for regional governments in a country that is already Europe's most decentralised state.
In French-speaking Wallonia - where unemployment is higher and the economy sluggish - there were fears this would leave their region worse off.
No single party bridges the linguistic and geographic gulf between Belgium's two regions.
Traditionally, the prime minister comes from one of the majority Flemish parties.

Belgian king rejects PM's resignation

BRUSSELS, Belgium (AP) -- Belgium's king refused to accept the resignation of the prime minister and his government, calling on key officials to redouble efforts to resolve a longtime disagreement over more self-rule for the country's Dutch and French speakers.

King Albert II on Thursday asked both politicians from both language camps to help sort out a deepening split over reforms that threatens to tear apart this nation of 6.5 million.

The Belgian monarch urged the politicians from Dutch-speaking Flanders and Francophone Wallonia to begin a "credible" dialogue about more regional autonomy.

He rejected, for now, Monday's resignation of the government of Prime Minister Yves Leterme. The royal palace said in a statement that the monarch asked Leterme "to encourage as best as is possible" chances of launching a constitutional reform debate.

Leterme offered the resignation after he failed to get his cabinet to agree on a future together by devolving more federal powers to Flanders and Wallonia. The unwieldy alliance comprises Christian Democrats, Liberals, Socialists and nationalist hard-liners from both language camps that took office March 20.

Efforts to grant Belgium's Dutch and French-speaking communities more self-rule began in the 1970s. Since then education, housing, trade, tourism, agriculture and other areas were shifted from the federal government, while Flanders, Wallonia and bilingual Brussels were given regional governments and parliaments.

Now Francophone parties accuse Dutch speakers of trying to separate themselves completely.

Flemish parties want their more prosperous, Dutch-speaking northern half of the country to be more autonomous by shifting corporate and other taxes, some social security measures, transport, health, labor and justice matters to the language regions.

Mainstream Flemish politicians say there is room for more regional autonomy in one country, but hardline nationalist parties in Flanders advocate the breakup of Belgium.