Amnesty International has urged the Mexican authorities to investigate an attack on human rights observers in the state of Oaxaca, that reportedly left at least two people killed and several injured and missing.

According to initial reports, an International Caravan of Human Rights Observers that were going to document human rights abuses in the Indigenous Triqui region, came under fire by armed men as they travelled in the area on Tuesday.

The organisation called on the Federal Attorney General to immediately investigate the incident.

Guadalupe Marengo, Deputy Americas Director at Amnesty International, said:

"Oaxaca authorities have for many years been unwilling to investigate grave human rights violations in that State. The Attorney General must now take immediate steps to protect those affected by the attack and carry out a full and impartial investigation."