About 100,000 Belgians have marched through central Brussels in protest at the new government's proposed reforms and cost-cutting measures, the first in a series of demonstrations and strikes planned over coming weeks.

Belgium's centre-right government, installed only a month ago, has pledged to raise the retirement age and limit scope for early retirement, cancel an inflation-linked wage hike due next year and cut the health and social security budgets.

Unions estimated about 120,000 workers, from dockers to metalworkers, as well as students, had gathered to protest in the capital. Police put the number at 100,000.

The unions plan a series of regional strikes every Monday starting on November 24, culminating in a national strike in December.

ACV union chief Marc Leemans said: "The signal is clear. People are angry, livid. This government's policies are totally unbalanced."

Prime Minister Charles Michel has invited union leaders to talks.