The Foreign Office has warned that UK oil workers are facing an increased threat of kidnapping in Iraq.
Officials have warned workers to be on alert in the southern province of Basra – home to Iraq’s oil and its gateway for exports.
The US embassy has also issued a warning to its citizens.
“Militant groups may be surveilling US citizens for possible kidnapping operations, particularly oil company employees working in Basra province,” the embassy said in a statement.
“The groups may be focused on US citizens at hotels in the Basra area.”
Exxon Mobil and Occidental Petroleum operate oilfields in Basra, while other American firms, Weatherford and Hallibuton, provide technical and logistic services.
The Foreign Office said in a statement last night that the US warning applied equally to UK 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.