MEXICO CITY - Police in northern Mexico have broken up three wildcat picket lines at assembly plants in the border city of Matamoros, across from Brownsville, Texas.

The government of the northern state of Tamaulipas said Sunday there were no registered strikes at the three plants and that some employees had asked for the blockades to be lifted.

Strikes broke out in January after President Andres Manuel Lopez Obrador decreed the doubling of minimum wages in border areas, apparently unaware that Matamoros plants had contracts that indexed salaries to the minimum wage.

After winning 20-per cent wages increases at 48 plants, flying squads of workers fanned out to other plants to seek the same increases, though those plants didn’t have the same contracts.

Picket lines continue at the local Coca-Cola bottling plant in Matamoros.