Nigerian militants said yesterday they opposed a bid by a Chinese energy group to secure 6bn barrels of crude reserves, comparing the potential new investors to “locusts”.

The Movement for the Emancipation of the Niger Delta told the Financial Times that the record of Chinese companies in other African counties suggested “an entry into the oil industry in Nigeria will be a disaster for the oil-bearing communities”.

“Our take on the Chinese is that we see them as locusts who will ravage any farmland in minutes,” said a Mend spokesman, although he added that “existing [oil companies operating there] are no better except that they adhere to standards under the right conditions”.

The comments came after the FT revealed that CNOOC, one of China's three big state-owned oil and gas groups, is in talks with senior Nigerian officials. The group hopes to secure 49 per cent stakes in 23 oil blocks partially or wholly owned by western oil companies in a deal that might be worth $30bn or more.

The proposals – which officials say are in the early stage of negotiations – would see CNOOC gain control over one in six barrels of crude in sub-Saharan Africa's biggest energy producer.

But the warning from Mend, the most vocal of the volatile delta's numerous rebel groups, underscores the difficulties the Chinese group would face in making such a sweeping entry into one of the world's most difficult oil frontiers.

At least one-third of Nigeria's oil capacity is shut because of attacks by militants, who have blown up pipelines and other facilities and kidnapped oil workers in the name of the people of the delta, who remain poor despite the oil wealth beneath their lands. The groups are also involved in a multi- billion-dollar trade in stolen oil.

Human rights activists have criticised China's readiness to work with regimes such as those in Sudan, Zimbabwe, Burma and elsewhere in its quest to secure resources.

Some Nigerian officials worry that the Chinese practice of importing its own staff will exacerbate resentment in the delta.

The government has sought to lure militants from the delta's creeks with pardons, stipends and the promise of training. But with just days to go until the amnesty's October 4 deadline, several senior militants have yet to give up their weapons.