Nigerian militants have released photos of foreign oil workers taken hostage a week ago. The Nigerian Red Cross is seeking access to the hostages, as local authorities say they are working to secure their release.

The hostages appear tired but unharmed in the photographs. In some of the pictures, heavily-armed militants, dressed in military uniforms and holding automatic rifles, machine guns and rocket-propelled grenade launchers, surround the captives.

The nine hostages: three Americans, a Briton, two Egyptians, a Filipino and two Thais - were kidnapped last Saturday by militants from a barge in the oil rich Niger Delta.

The Nigerian Red Cross says it has, so far, failed in its efforts to gain access to the hostages to determine their condition.

"We are still working really hard, because the location of the hostages and those who are keeping them is really shrouded in secrecy," said Patrick Bawa, a spokesman for the Nigerian Red Cross. "The government of Delta state set up a committee, and the Red Cross is working with that committee to ensure that we get an in - [a] way in to where the hostages are. But that, as I said, has proven very difficult. But, we are also linking up with the Ijaw community leaders to assist us in doing that."

Local officials say substantial progress has been made in talks to release the captives. However, the hostage-takers have denied any contact with the mediators.

The militants have threatened to kidnap more foreign oil workers in the delta. They have also warned of more attacks on oil facilities in a bid to cripple Nigeria's oil exports. Output has already been cut by a fifth in the West African nation, the continent's largest crude oil producer.

The militants are demanding the release of two jailed ethnic Ijaw leaders and more control of the region's oil wealth.

Meanwhile, a Nigerian court has ordered Royal Dutch Shell to pay $1.5 billion to the Ijaw people of the Delta region. The Ijaw have been fighting since 2000 for compensation for environmental degradation in the oil-rich region. They took the case to court after Shell refused to make the payment ordered by Nigeria's parliament.

Shell says it believes there is no evidence to support the claim, and will appeal against the ruling.