Nigeria's relations with western oil companies have long been volatile. They are now coming under extra strain. Violence in the Niger delta, theft of oil and underinvestment are costing billions of dollars in lost revenue each year. Government plans to overhaul the industry have heightened tensions.

On top of this, a Chinese bid to wrest control of a sixth of Nigeria's proven crude reserves risks bringing matters to a head. State-owned CNOOC's offer for stakes in 23 prime oil blocks, all of which are part or wholly controlled by western oil groups, may have strengthened Nigeria's negotiating hand. This, at a time the government wants to impose higher costs on the companies, renegotiate contracts and win a better price for the renewal of licenses that expired last year. The Chinese are offering better terms. In effect, western groups are being asked to put up or shut up.

For Nigeria there are dangers in this brinkmanship. The country depends on oil and gas for more than 90 per cent of its foreign currency earnings. This year production is down a third. Litigation – should the companies be forced to relinquish shares – would increase the turmoil. It would also be a distraction from the principal task at hand – restoring stability to the Niger delta, and restructuring the oil industry in a way that delivers fairer returns to all Nigerians. Also, what they gain from China's higher offer they could lose in less effective recovery of oil.