Thousands of protesters have marched in Mexico City following the murder of an environmental activist, BBC reported.

Samir Flores Soberanes, who was also a journalist, was shot twice in the head in his home in Amilcingo, south of Mexico City, on Wednesday.

The protesters held signs saying "Samir didn't die, the government killed him"; "Samir lives"; and "Justice for Samir".

As the march made its way through Mexico City, thousands gathered in Amilcingo to lay Flores to rest.

The reasons for the killing are not yet clear but a prosecutor has indicated it was linked to organised crime.