Belgium was in chaos Monday, just hours before an EU summit, with transport and other public services halted by a national strike called by unions in protest at EU-ordered austerity measures.

It is the first such general strike in Belgium since 2005 and the first since 1993 launched jointly by the country's three main unions, which are angry over public spending cuts of more than 12 billion euros ($15 billion) for 2012.

Belgian rail workers began their industrial action late Sunday, with the first trains stopping around 9:00 pm (2000 GMT).

High-speed international services on Eurostar and Thalys and inter-city Belgian trains were also all halted on Monday, and no buses, trams or metro trains were running.

At Brussels airport, several flights were cancelled and others delayed, while Charleroi airport -- a key low-cost hub in the south of the country -- was closed. Postal workers and staff at the port of Anvers, one of the biggest in Europe, also downed tools.

Strikers were also planning blockades on Belgian roads.

The Belgian government has had to arrange fallback emergency access via a military airport for European Union leaders arriving for the summit, which opens at 1400 GMT.

Staff working in the summit venue in Brussels were warned they might have to turn up before 5:30 am to escape picket lines.

Announcing the strike last week, union leaders said it was "inevitable" after tense negotiations with Socialist Prime Minister Elio Di Rupo's government.

They said the strike was "patently required to convince the government and employers to take fully into account the social reality for workers and those on benefits".

The three union movements which called the strike said negotiations with the government on further likely spending cuts demanded by EU partners to stay within set deficit targets had proved "inconclusive".