Britain on Wednesday lowered its travel warning for Arbil in Iraqi Kurdistan, prompting some oil companies to return foreign employees who had been evacuated as violence escalated.

Canadian oil producer Oryx Petroleum said it had restarted oil production at its Demir Dagh field, while Gulf Keystone Petroleum said it was returning around 50 foreign staff to its sites in the area.

"In terms of getting outside contractors in there to continue the work on their developments, they are now coming back in as of this week," said a spokesman for Gulf Keystone.

The energy firm, whose oil production in the region was not materially affected by the evacuations, said last week the return of international staff was essential to meeting a year-end target to increase oil output at its flagship Shaikan field.

Genel, the operator of the region's largest producing oil fields, was considering returning staff it had previously evacuated, a person familiar with the company said.

Kurdistan-focused Afren said its staffing situation remained unchanged after it shut down production at its Barda Rash field in Iraqi Kurdistan last month. - Reuters