Violence in Darfur spread beyond its borders on Thursday as rebels claimed to have struck a Chinese-backed oil field in a neighbouring Sudanese province, dealing a further blow to fading hopes that peace talks due to start on Saturday will resolve the conflict.

The Justice and Equality Movement (Jem), one of Darfur’s fractious rebel groups, said it had attacked the Defra oil field in Kordofan province on Tuesday and kidnapped two foreign workers, a Canadian and an Iraqi.