BOGOTA (Reuters) -Colombia's leftist President Gustavo Petro on Wednesday signed a decree to hold a referendum on labor reforms, an attempt to force the Senate to vote on a proposal on the matter before their session wraps up later this month.

The referendum proposal seeks to limit the working day, increase the surcharge for Sunday and holiday work from 75% to 100% and require social security payments for delivery app drivers.

The Senate is currently debating a modified labor reform, after in May rejecting a 12-question version of the referendum in a tight 49 to 47 vote, which Petro later alleged was fraudulent.

The legislature's current session ends on June 20.

Petro and his interior minister, Armando Benedetti, said that if the reform passed, the referendum would be called off.

If the referendum were to be held, each measure would need to be approved by the majority of at least 13.5 million voters, a third of Colombia's electoral roll, to be valid.

Opposition parties have said Petro's decree is tantamount to a coup, violates the country's constitution and destroys the separation of powers of Colombia's three branches of government.

Analysts have warned, meanwhile, that the decree could face legal challenges, including in the Constitutional Court.

A majority of the social and economic reforms promised by Petro - who was elected in 2022 on pledges to right centuries of inequality in the Andean country - have been rejected by lawmakers.

Colombia will hold legislative and presidential elections in the first half of 2026.

(Reporting by Carlos Vargas and Nelson Bocanegra; Writing by Natalia Siniawski; Editing by Gabriel Araujo, Kylie Madry and Diane Craft)