The key Iraqi oil town of Kirkuk was reported to have been rocked by two huge explosions on Thursday amid an offensive against Kurdish defence forces by militant group Islamic State (IS).
Plumes of black smoke were seen rising over the city as ambulances rushed to the scene, according to Reuters.
There was no immediate word on any casualties after the blasts, although the BBC was reporting that six people had been killed after a car bomb had exploded near a Shia mosque in the northern Iraqi town, which is being defended by Kurdistan’s Peshmerga army.
IS was reported to have captured the town of Qaraqosh in Nineveh province after the withdrawal of Kurdish forces, resulting in a mass exodus of its largely Christian population.
The jihadist group now controls large areas of northern Iraq near the semi-autonomous region of Kurdistan, where international companies such as DNO and Genel Energy are operating.
London-listed Gulf Keystone Petroleum issued a statement in which it said its Kurdistan operations, including the Shaikan field, “remain safe and secure”.
“While there is no immediate threat to any of the company's operations in the region, we continue to monitor the situation closely and operate with increased security as a precaution,” it stated.
Oslo-listed DNO, which operates the key Tawke oilfield and derives about 55% of its revenue from Kurdistan, said earlier this week its operations in the region were continuing, although it is also monitoring developments with staff security as its top priority.
The ongoing turmoil in Iraq has though hit the share prices of both companies, with DNO sinking 7.7% and Gulf Keystone down more than 7% at around 15:30 CET on Thursday.
London-listed Genel Energy, which operates the Taq Taq field in Kurdistan and is also a partner at Tawke, saw its share fall by nearly 5.78%.
Canada’s Oryx Petroleum, which has made several light oil finds on its Hawler licence in the semi-autonomous region in the past year, said on Wednesday that its operations were also continuing safely.
Other companies with operations in the region include London-listed Afren and Hungary’s MOL.