The Nigerian government said Tuesday it is in advanced talks with China's CNOOC Ltd. (CEO) over signing deals on several onshore oil blocks as the state-run company looks to expand its position in the West African nation by securing drilling rights going unused by Western energy firms.

Companies such as Anglo-Dutch Royal Dutch Shell PLC (RDSA) have long been at loggerheads with the Nigerian government over not fully utilizing some of their drilling licenses, often for not having secure enough operating conditions due to militant attacks on pipelines and other oil infrastructure.

"We are in talks with many companies at the moment and certainly CNOOC is one of those. They have been a good company for us and we will see what happens," Nigerian Oil Minister Rilwanu Lukman said by telephone.

An official with Nigeria's state oil company said the number of onshore blocks on offer was about 20 and that negotiations were at a late stage with some of those firms, including CNOOC.

The official said he was unsure exactly how much crude CNOOC was vying for but said targeted investment would run into several billion dollars.

While any deals would beef up its petroleum presence in the country, China's record in recent years in converting deals in Nigeria into new crude production has been lackluster, often for government bureaucratic reasons.

Chatham House, a U.K. think tank, earlier this year published a study highlighting how a series of oil deals Asian oil companies, including Chinese state-run firms, signed with the Nigerian government back in 2004-2005 in exchange for bankrolling infrastructure projects had generally failed to produce their intended result.

The biggest reason for the failure, it said, was the Nigerian government's lack of "follow-up mechanisms to enforce the deals."

It is unclear if CNOOC is offering to stump up wads of cash on more non-oil projects in the latest round of contract negotiations.

The Nigerian government is hoping a recent lull in militant violence in the country's main oil-producing Niger Delta region will continue so producers can restart operations in various areas.

The International Energy Agency in Paris estimates that around 500,000 barrels a day of oil production capacity has been shuttered in Nigeria over the past several years due to militant attacks. Getting that capacity back into service has been routinely hobbled by security problems. Nigeria currently pumps around 1.8 million-1.9 million barrels a day.

"We think conditions are improving so that production can get going again in many areas," the official with Nigeria's state oil company said.

Analysts, however, say the government's policy of paying militants to lay down their arms has generally failed because the root causes of the militancy - poverty and lack of education and life opportunities - haven't been tackled.

The Nigerian government has grown more critical of U.S. and European oil companies - still the biggest operators in Nigeria despite the influx of Asian companies the past five years - for not fully utilizing their onshore drilling licenses. Analysts say the criticism is a bargaining tactic.

In the past year or so, Shell has sold some of its unused drilling rights in the country to other companies. Shell is still looking to sell some additional oil acreage in Nigeria but not on a large scale, a person familiar with the matter said Tuesday.

CNOOC officials couldn't be reached for comment.

-By Spencer Swartz, +44 207 842 9357; spencer.swartz@dowjones.com

(James Herron, Benoit Faucon, and Yvonne Lee contributed to this article.)