BAGHDAD, May 22 (Reuters) - U.S. and British citizens, particularly oil workers, in the southern Iraqi province of Basra may be at risk of kidnapping by militant groups, the U.S. Embassy and British officials said.
Basra is home to most of Iraq's oil and its gateway for exports.
"Militant groups may be surveilling U.S. citizens for possible kidnapping operations, particularly oil company employees working in Basra province," the embassy said in a statement late on Wednesday. "The groups may be focused on U.S. citizens at hotels in the Basra area."
Exxon Mobil and Occidental Petroleum operate oilfield concessions in Basra, while other American firms, Weatherford and Hallibuton, provide technical and logistic services.
The British Foreign Office said in a statement on Thursday the U.S. warning applied equally to its own citizens, particularly oil company employees working in Basra province.
Iraqi officials in Basra denied receiving any signs of possible threats to foreign workers in Basra.
Last November, a British oil worker from Schlumberger was attacked in Basra when he removed religious flags by his work site in the Rumaila oilfield. The incident caused some international firms to temporarily pull their workers from Iraq.
Basra, which has a Shi'ite majority, has been affected by the rise in violence that has shaken Iraq over the last year and a half. Several Sunni residents in Basra province have been killed in recent months, including a candidate in last month's election.
Local Shi'ites and Sunnis suspect Shi'ite militia groups are behind the killings, but others have blamed a hidden cell of Sunni militants.
Posters for Shi'ite militia fighters killed in Syria defending Shi'ite shrines are displayed prominently in the city.
(Reporting By Ned Parker; Editing by Janet Lawrence)