Mexico's President Enrique Pena Nieto has received a leading Venezuelan opposition activist for the first time, in a policy shift that reflects Mexico's increasing assertiveness against the government of Venezuela's President Nicolas Maduro.

Pena Nieto's meeting with Lilian Tintori, wife of jailed opposition leader Leopoldo Lopez, in the Mexican capital follows statements by the Mexican government demanding that democracy be "re-established" in Venezuela, where elections have been postponed.

"We trust that, via an agreement between all sides, it will be the Venezuelans who re-establish the democratic order," Pena Nieto said via Twitter late on Thursday after the meeting.

The position reflects deep concern about the humanitarian crisis of food and medicine shortages in Venezuela, as well as the Supreme Court's short-lived decision last week to take over the powers of the country's opposition-controlled Congress.

It is also seen by diplomats as helping support ties between Mexico and the government of US President Donald Trump.

Venezuela's Foreign Minister Delcy Rodriguez last week slammed her Mexican counterpart Luis Videgaray's "betrayal" and called him "servile" after Videgaray said the situation in Venezuela was a "systematic violation" of democratic principles.

Mexico has taken a leading role in efforts at the Washington-based Organisation of American States (OAS) to pressure the Maduro government under threat of being expelled from the regional diplomatic body.

"Pena Nieto is worried about what Venezuelans are living, Tintori said in an interview with Mexican media network Grupo Imagen that also referred to Mexico's role in the OAS.

The Mexican stance against Maduro's government is a shift from a traditional neutral approach to the politics of its Latin American neighbours. It brings Mexico in line with recently elected conservative governments in Argentina, Brazil and Peru but puts it at odds with Venezuela's allies in the region.

Some in Mexican foreign policy circles had been pushing for Pena Nieto to receive Tintori as a message of support for the Venezuelan opposition. Tintori had previously met Videgaray's predecessor as foreign minister.

Reuters