International oil producers have been hit hard by the Nigerian government's attempt to follow the production quotas imposed by the Opec oil cartel.

Royal Dutch/Shell, Nigeria's largest foreign oil producer has said its February output fall to 647,000 barrels per day, 24% down from the average volume produced this time last year.

TotalFinaElf said its production in the West African country was 20% down over the past year due to the restrictions introduced by Nigeria's government.

"TotalFinaElf production is affected, as are all oil and gas companies operating in Nigeria", the company said.

Quota buster

Within Opec, Nigeria has a reputation of being the cartel's biggest quota cheater.

Opec has blamed Nigeria for the overproduction of some 300,000 barrels per day above its assigned quota of 1.8 million barrels per day.

Those accusations increased late last year when the cartel was trying to boost oil prices by cutting production.

In an attempt to improve its profile and attract foreign investment, the government has made new efforts to meet the assigned quotas from January, when Rilwanu Lukman, Nigeria's presidential oil adviser also became the Opec president.

The country said it cut its oil production by 180,000 barrels per day in January and has continued to make cutbacks.

Guarded secret

It is expected that the country will keep its April crude oil exports unchanged from the March estimated level of 1.5 million barrels per day, slightly above the cartel's limit.

But the moves to enforce a quota discipline were overshadowed when the Nigeria's Department of Petroleum Resources classified all the production data as a national secret.

Traders are now wondering how real the export volumes and promised cuts actually are.