Protesters block Mexico onshore oil wells - Pemex

MEXICO CITY, Feb 5 (Reuters) - Protesters are blocking onshore oil wells and crude installations in the southern Mexican state of Tabasco, causing lost crude production, the state oil company Pemex said on Tuesday.

It was not clear how much production was being lost by the protests, which were called by a former presidential candidate who is opposed to government attempts to boost private investment in parts of the state-run sector.

Pemex spokesmen were not immediately available to quantify lost output by the protests and the monopoly did not say when the protests started. Online newspaper Reforma said 13 wells were being blocked.

"The constant blockades of oil installations affects production and stops the productive activities from being carried out, with the consequent economic damage to Pemex, public finances and the activity of the state," Pemex said in a statement.

Without saying how many wells or fields are affected, Pemex called on the protesters to stop blocking the installations and allow Pemex staff to enter and retake control and undertake maintenance and secure the installations.

Reforma newspaper said hundreds of supporters of ex-presidential candidate Andres Manuel Lopez Obrador were blocking Pemex sites in Tabasco.

Lopez Obrador is a leftist who has lost most of his political power since being narrowly defeated by conservative Felipe Calderon in 2006 presidential elections. (Reporting by Chris Aspin; Editing by Gary Hill)