LEGISLATORS in Colombia have once again blocked President Gustavo Petro’s efforts to overhaul the country’s employment laws.

On Wednesday, the parliament rejected Mr Petro's call for a referendum on whether working days should be limited to eight hours and whether there should be double pay for working during holidays.

Mr Petro asked Congress earlier this month to approve the 12-question referendum to give voters a chance to decide on the changes that legislators themselves had already rejected twice.

He had warned politicians against blocking the referendum, saying in a speech to thousands of people at an International Workers’ Day demonstration on May 1 that if they did not approve it, Colombians would punish them at next year's legislative elections.

Following an intense debate on Wednesday, 49 senators voted against the measure and 47 in favour.

Mr Petro, Colombia's first left-wing president, characterised the vote as fraudulent. He has repeatedly accused politicians of blocking his social initiatives and ignoring popular demands.

Had senators approved the referendum, voters would have been asked questions such as whether daytime working hours should end at 6pm and whether open-ended contracts should be offered to workers to prioritise job stability.

In a rarely used manoeuvre, a group of congressmen successfully appealed on Wednesday against the March dismissal of Mr Petro’s proposed employment reform.

This step allows politicians to debate his proposals again and potentially approve them. They face a June 20 deadline to do so.