Unidentified gunmen have kidnapped three Indians from a residential area in the southern Nigerian oil city Port Harcourt.

The Indians' employer was not immediately known.

The gunmen blasted the front gate of the residential compound, killed a Nigerian and kidnapped the three, reports said, quoting police officials.

Reports said security forces intervened just in time to save seven other Indians in the compound.

Kidnappings of foreign workers have become frequent in the country's troubled Niger Delta region since 2005, when a militant group started using abductions in its campaign against the Nigerian government and oil companies. Criminal gangs have since taken up the practice.

Nearly 100 foreigners have been kidnapped since the beginning of the year -- nearly double the entire total for 2006. Hostages are generally released unharmed after a ransom is paid. More than a dozen foreigners remain in captivity.