MEXICO CITY, March 7 (Xinhua) -- UN agencies on Tuesday condemned the killing of a Mexican journalist in the southern state of Guerrero.

The Office of the United Nations High Commissioner for Human Rights (OHCHR) and the UN Educational, Scientific and Cultural Organization (UNESCO) issued statements respectively decrying the death of Cecilio Pineda Birto.

Armed men on a motorcycle opened fire on Pineda in the city of Altamirano on Thursday as he waited outside a car wash for his vehicle, according to media reports.

Mexican authorities knew Pineda had received death threats, apparently for his investigative reports on local organized crime.

"No attack against a media outlet or a journalist should go unpunished," OHCHR representative in Mexico Jan Jarab said.

"It is essential to have more information about the measures of protection that Pineda Birto could have been given to prevent this tragic incident, so that similar events can be prevented in the future," Jarab added.

UNESCO Director-General Irina Bokova also condemned the slaying, saying "I call on the authorities to spare no efforts in bringing the perpetrators of Cecilio Pineda Birto's killing to justice."

Pineda contributed to several well-known publications and also reported on crime via a social media account.