The Interfax news agency has reported that the Niger Delta Militant Force Squad had demanded almost $US 500,000 US on Thursday for the release of six employees from the Russian aluminium company Rusal, who were kidnapped in the Nigerian state of Akwa Ibom

Rusal, however, says the statement does not correspond to the real situation.

The hostage-takers also called for improved working conditions for Nigerians in exchange for the release of the hostages.

The kidnapped Russians include five employees of the company and one family member.

Shortly after the incident, Foreign Minister Sergey Lavrov outlined Russia's response, saying Moscow was working with regional authorities to free the hostages.

“We have been in contact with the government of Nigeria from the very first moment.  We are also in touch with the governments of neighbouring coountries who could be of help, in particular with the government of the Republic of Guinea. We're working closely with representatives of the Rusal company, who are getting visas now. Hopefully tomorrow they will depart to Nigeria in order to settle the issue as soon as possible,” said Mr Lavrov.

Nikolay Patrushev, the director of Russia’s Federal Security Service, said that freeing the Russians is a priority, but force will not be used and diplomatic negotiations are the only option.

The Governor of the area where Rusal is based has promised that the hostages will be released soon, and has advised against conducting direct negotiations with the hostage-takers.

Foreigners working in the oil industry in Nigeria consantly live under threat of kidnap by militant groups or angry locals.

Nigeria is the most populous country in Africa. Petroleum accounts for 40% of its GDP, and the country is the world's 12th largest oil producer, and the 8th largest exporter.

But while foreign companies harvest Nigeria's vast energy treasures, many local residents live in poverty.

Despite its wealth, Nigeria is an unstable country with a long history of poitical unrest and military coups.