Nigerian police kill four kidnappers after hostage escapes

Criminal gangs kidnapping for ransom have blighted Africa's second largest economy for years, with the vast majority of people abducted Nigerians, although foreign oil workers have also been targets.

Violence and crime in the oil-producing Niger Delta pushes up the cost of doing business. Shell spent almost 40 percent of its global security budget in Nigeria between 2007-2009, according to an oil industry watchdog.

Senior civil servant Benson Ojoto was kidnapped earlier this month in Delta, one of the three states that make up the bulk of the Niger Delta. He was freed on Sunday, police said.

"Luckily, the man escaped while the gang headed to Edo with his car. We trailed them to Benin city where we engaged and gunned down four of them. One escaped with gunshot wounds," Delta state police spokesman Charles Muka said.

Muka said they strongly suspected the gang was behind the kidnapping this month of Delta State Judge Marcel Okoh, who has since been released.

Although the majority of kidnappings in Nigeria are for financial gain, this year there have been a handful of abductions of foreigners by Islamists in the largely-Muslim north, far from the oil region.

A Briton and an Italian were killed during a raid in northeast Sokoto in March and a German died during another rescue attempt in Nigeria's second-largest city Kano in May.

(Reporting by Anamesere Igboeroteonwu; Writing by Joe Brock; Editing by Jon Boyle)