Mexico on Wednesday called on the United States to do more to ensure that the rights of migrant agricultural workers are protected under a North American free trade agreement. The government has written to US Labor Secretary Marty Walsh to voice concerns that Mexican workers are not getting the protection to which they are legally entitled, the foreign ministry said. Factors such as "ignorance, fear and abuse on the part of some employers prevent migrant workers from fully exercising their labor rights in some industries and states," it said in a statement. Workers in the protein packaging and processing industry also needed better protection, it said. Problems faced by Mexican migrant workers include a lack of payment of wages and overtime as well as the right to collective bargaining, according to the ministry. Sanitary measures to prevent the spread of Covid-19 were also sometimes inadequate, it said. Under pressure from former US president Donald Trump, Mexico and Canada renegotiated the 1994 North American Free Trade Agreement with the United States, which was replaced last July by the US-Mexico-Canada Agreement. Earlier Wednesday, the United States said it had invoked a provision in the agreement to ask Mexico to investigate allegations of wrongdoing in a union vote at a General Motors factory. Mexican President Andres Manuel Lopez Obrador welcomed the request and said he would respond quickly. jg/dr/st