Sudanese rebel forces released 29 Chinese workers kidnapped ten days ago in the main oil-producing state of South Kordofan, where the army has been fighting insurgents for seven months, Sudan’s foreign ministry said on Tuesday.

The incident had been an embarrassment for the Sudanese government, which is trying to boost investment from China, its main political and trade ally, as it seeks to overcome an economic crisis.

Rebels of the SPLM-North said they had taken the construction workers for their own security after a battle with the Sudanese army in South Kordofan, which borders newly independent South Sudan.

But the workers had become caught up in a dispute between Khartoum and rebels who are trying to attract attention to the plight of 417,000 civilians who have fled fighting in South Kordofan and Blue Nile.