Jan. 11 (Bloomberg) -- Militants operating in Nigeria’s oil region have issued the first photographs of two British oil workers held hostage for four months.

The Movement for the Emancipation of the Niger Delta, or MEND, said the release of Robin Hughes and Matthew Maguire was tied to freedom being granted to its detained leader.

“We intend to hold on to them for as long as a very sick and dying Henry Okah is held hostage by the Nigerian state,” MEND spokesman Jomo Gbomo said in an e-mailed statement. “God forbid that Henry Okah should die in detention.”

Hughes and Maguire were among 27 oil workers, including five foreign nationals, seized by gunmen who hijacked their vessel on Sept. 9 in the Niger Delta. MEND said afterwards it rescued them from their attackers and freed all except the two Britons. MEND has accused the U.K. government of supporting Nigeria’s President Umaru Yar’Adua.

Attacks by MEND and other armed groups on Nigeria’s oil industry have cut the country’s exports by more than 20 percent since 2006. The country is Africa’s leading oil exporter and the fifth-biggest source of U.S. oil imports.

To contact the reporter on this story: Dulue Mbachu in Lagos at dmbachu@bloomberg.net

Last Updated: January 11, 2009 12:02 EST