Hardline trade unions staged protests across France against an overhaul of labour rules expected to be passed by parliament later in the day, a show of force they hoped would mobilise public opinion for further labour action.

The lower house of parliament, where President Francois Hollande's Socialist government has a slim majority, is expected to pass his measures loosening firing and hiring rules, opening the way for a Senate vote on April 17.

Some trade unions, led by the left-wing CGT and backed by hard-left allies in parliament, were determined to stir up opposition against what they called a "traitorous" bill, with marches in up to 170 towns and cities.

Al Jazeera's Jacky Rowland reports from Amiens in northern France.