Elio di Rupo will be Belgium's first prime minister from francophone Wallonia since 1974 [EPA]

Belgian politicians have finally agreed to form a government after record-long talks finally led to the creation of a six-party coalition tasked with implementing the most profound state reform in decades and restoring the country's finances.

The government, announced late on Monday and due to be sworn in on Tuesday almost 18 months since the last elections in June 2010, will be headed by Elio Di Rupo, the French-speaking Socialist leader.

Di Rupo is the first Belgian prime minister to come from the francophone region of Wallonia since 1974, as well as the first son of immigrants and the first openly gay person to lead the government of the bilingual country.

Di Rupo's government retains many of the ministers from the caretaker government of Yves Leterme, the current acting prime minister, albeit in different roles.

Steven Vanackere, a Flemish Christian Democrat, becomes finance minister and Didier Reynders, a francophone Liberal, foreign minister in a straight job switch.

The government must satisfy demands of the Dutch-speaking Flemish majority for devolution of further powers to Belgium's regions, and may have to redraw a budget that economists say is based on too optimistic a growth forecast.

The more right-leaning Flemish electorate has already expressed concern about being led by a French-speaking Socialist, and one whose command of Dutch is considered limited.

A poll in Le Soir newspaper showed just 29 per cent of Flemish people had confidence in Di Rupo, although his support in French-speaking Wallonia was 69 per cent.

Talks including N-VA, a party that wants Flanders to break free from Belgium, were deadlocked for months, prompting speculation that 181-year-old Belgium could break apart.

The N-VA's eventual exit opened the door for a deal resolving electoral boundaries around the capital Brussels, devolution of more powers to the regions and financial transfers, issues over which Belgium's linguistic groups have argued for years.

Belgium also has a budget battle on its hands and might be forced to toughen austerity measures that drew 50,000 protesters onto the streets last Friday.

Belgium has found itself in an uncomfortable middle ground between triple-A rated eurozone countries and those at the periphery of the single currency bloc whose sovereign debt has been sharply sold off since the start of last year.

Belgium's public sector debt totalled 96 per cent of gross domestic product last year, putting it behind only Greece and Italy in the eurozone and on a par with Ireland.

It has also been saddled with providing the bulk of state guarantees to the bailed-out Franco-Belgian financial group Dexia.