Violence against the industry in Nigeria's southern Niger Delta has shut down a fifth of the country's production capacity for the past two years, and there have been attacks on ships and rigs far out to sea in the Gulf of Guinea.

"President Yar'Adua said that he had discussed the establishment of the Guard Force during his recent visit to Washington and expected the United States government to help the Gulf of Guinea Commission with logistics and training for the force," Yar'Adua's spokesman said in a statement on Friday.

Yar'Adua was speaking on Thursday at a meeting with President Teodoro Obiang Nguema Mbasogo of Equatorial Guinea, which also has oil facilities in the Gulf of Guinea and is concerned about threats from Nigerian militants.

The Gulf of Guinea Commission, which includes countries that border the gulf as well as the United States and Britain, has been talking about setting up an international force in the region for years but little progress has been made so far.

The U.S. navy, keen to help protect oil assets that provide a major supply line to U.S. refineries in the Gulf of Mexico, has conducted joint patrols and training exercises with Equatorial Guinean vessels and has offered help with logistics.

But Nigeria, Africa's biggest oil producer and a major regional power, has been cagey about allowing a foreign presence in the Gulf of Guinea despite its navy being unable to secure the area.

Most of Nigeria's oil is produced in the swamps and shallow coastal waters of the Niger Delta, but two giant deep-water fields began pumping in 2006 and two more are due to start this year.

As well as militants from the Niger Delta seeking greater benefits for local communities and political autonomy, pirates and oil smugglers move freely off the coast of Nigeria where oil industry vessels are frequently attacked.

Dozens of foreign and Nigerian crew of oil vessels and rigs have been taken hostage by ransom seekers in Nigerian waters in the past two years. Almost all were released unharmed.