In ordering the 154 Sudanese to leave, the Sudanese Foreign Ministry said it was working with its South Sudanese counterpart to discuss the possibility of sending a plane from Khartoum to fly the workers out, the Sudan Times reported Tuesday.
Ministry spokesman al-Obaid Adam Marawih said the Sudanese employees for Petrodar worked in the Fulug oilfield in South Sudan's Upper Nile state.
Tension between Sudan and South Sudan can be traced, in part, to the inability to agree on terms of using Sudan-based pipelines to export oil from South Sudan, the Times said.
South Sudanese President Salva Kiir was in China Tuesday, with plans to ask Beijing to help finance an alternative pipeline for exporting oil from his country.
During Kiir's visit, Chinese President Hu Jintao urged calm and restraint between Juba and Khartoum, asking them to negotiate their differences rather than fuel tensions, China's state-run news agency Xinhua reported.
Chinese officials said Zhong Jianhua, the country's envoy on African affairs, will visit Sudan and South Sudan to try to promote dialogue and negotiations.