At least 10 people working for state-run Pemex have been abducted in the southern Mexico states of Chiapas and Tabasco by groups presumed to be linked to the Zetas, among the most violent drug hitmen, Reforma newspaper said.

Pemex declined to comment, Reuters reported.

"John Doe," a worker who made under $1000 per month, told Reforma he was kidnapped in July as he left work at a Pemex facility in Chiapas by an armed man and a woman who later demanded a $160,000 ransom from his family. He was released five days later for a fraction of the original demand.

He said about 30 Pemex staff had been abducted in Chiapas alone this year.

"Jorge," a higher ranking Pemex official who earned a monthly salary of about $6400, was kidnapped in Tabasco for 20 days. His abductors cut off his left thumb and sent it to his family to prompt the $400,000 ransom for his release, the paper said.

The spate of kidnappings of Pemex workers comes against the backdrop of a brutal drug war that has killed more than 31,000 people since President Felipe Calderon launched his military campaign on cartels when he took office in 2006.

Nestor Martinez, who managed a production unit for Pemex in Tabasco, was abducted earlier this year, industry sources told Reuters in May.

The executive, who also led the national petroleum engineers' association, was released after paying a hefty ransom.

Extortion of businesses and kidnapping is common in certain parts of Mexico. Many abductions are not reported because of a widespread mistrust of Mexico's police.

Businesses often deal with private security experts rather than the police when executives are abducted and they usually try to keep cases quiet for fear of attracting more criminal attention.

Published: 08 November 2010 19:41 GMT | Last updated: 08 November 2010 19:41 GMT Getting