MEXICO CITY (Reuters) - A group representing some of Mexico’s biggest companies told left-wing President Andres Manuel Lopez Obrador on Monday that politicians should resist “extortion” by labor unions after strikes and blockades in recent weeks.

FILE PHOTO: State police armoured vehicles patrol at an industrial park where employees from some plants are on strike in Matamoros, state of Tamaulipas, Mexico Janaury 29, 2019. REUTERS/Stringer

Alejandro Ramirez, president of the Mexican Business Council, said strikes at factories in the northern state of Tamaulipas and blockades of railways by a teachers union had caused more than a billion dollars in losses and could cause businesses to close.

Members of the group, including Mexico’s second-richest man, German Larrea, who controls mining and transport conglomerate Grupo Mexico, were critics of Lopez Obrador before his July 1 election, warning voters should be wary of populism.

“In labor matters, we look favorably on Mexicans starting a new era of union freedom that will allow the end of old protectionist practices for a few unions and companies,” said Ramirez, chief executive of cinema chain Cineopolis.

“Freedom of association and respect of the rule of law should be the axis of this new labor reform. For that reason, we make a respectful call to lawmakers of all parties that it doesn’t just guarantee union freedom but also avoids union extortion.”

Since taking office, Lopez Obrador and members of the ruling party have sought regulation in areas ranging from banking and pensions to mining to make services cheaper for consumers.

The former Mexico City mayor wants to encourage investment to drive growth, but some worry regulation will be heavy handed and unpredictable.

MORENA, the party created by Lopez Obrador, is planning a reform to make it easier for workers to form independent unions. Traditionally, unions have allied with the former party of power, the Institutional Revolutionary Party.

Lopez Obrador brought veteran union leader Napoleon Gomez into his party as a senator. Gomez has a history of conflict with Grupo Mexico, including strikes.

Gomez last week founded a federation called the International Workers Confederation.

Monday’s event was the first time the group met with Lopez Obrador since he took office in December. Earlier in the day, he met the Council for Investment Promotion, Job Creation and Growth, a body he created to advise on economic policy.

Labor strikes in January at manufacturers in the Mexican city of Matamoros on the U.S. border cost about $50 million a day in unfulfilled international contracts.

Teachers from the National Committee of Education Workers blocked railroad tracks for weeks in January to protest labor demands.