Gunmen kidnapped six Russians in Nigeria's lawless southern oil-producing region, while security forces liberated two Filipino seamen in a deadly gunbattle.
Gunmen blew up the Russians' homes with dynamite before taking them away, said Felix Nxong, the general manager of the plant in southern Akwa Ibom state. Russian officials confirmed the abductions and said one Nigerian driver was killed.
Separately, the Filipinos were taken from their boat in the waters of the Niger Delta late Saturday, but were rescued only hours later by police who attacked their captors, killing one hostage-taker, said Rivers State Police Commissioner Felix Ogbaudu.
More than 200 foreigners have been kidnapped since militants increased their attacks in late 2005, with more than 100 foreign workers taken this year alone as criminal gangs have joined the militants in hostage takings.
Hostages are generally released unharmed after a ransom is paid.
On Saturday, the Nigerian militant group whose oil-region attacks have spurred global crude prices higher announced a one-month cease-fire, offering newly inaugurated President Umaru Yar'Adua an opening to solve the crisis that has roiled Africa's oil giant.
The Movement for the Emancipation of the Niger Delta did not offer to stop kidnapping foreign oil workers, but it released six hostages it had been holding, saying the liberation of the four Italians, one American and one Croatian taken hostage May 1 was an olive branch to the government.
The group launched its campaign of kidnappings and oil-installation bombings in December 2005, seeking to force the federal government to give its impoverished region a greater share of oil funds.
In his inaugural speech Tuesday, Yar'Adua called the conflict an urgent matter and asked for a permanent cease-fire to allow for mediation toward a long-term peace.
However, the announcement is not likely to immediately calm the vast southern region where numerous criminal gangs and militant groups ply the swamps and creeks in gunboats. Violence continued Saturday, with gunmen seizing four more foreign hostages in the main oil center of Port Harcourt. Some two dozen foreigners are currently in captivity.
The group said it would continue the kidnappings of foreigners, which have become a near-daily occurrence and no longer affect oil prices overseas. But it said Saturday's release showed "a preparedness to dialogue with a willing government."
Nigeria is Africa's top crude producer, an OPEC member and a leading exporter of oil to the United States.
The rising violence in Nigeria comes amid tight global oil supplies around the world, increased demand from China and India and turmoil in the Middle East, meaning the militants' attacks on oil infrastructure have had great effect on prices overseas.