Nigerian security forces say they arrested several alleged kidnappers during an operation on Wednesday to rescue a Canadian woman seized by gunmen in northern Nigeria. The suspect is due in court on Thursday.

Security forces have intensified their search for those behind the mid-April abduction of Julie Ann Mulligan, a 45-year-old Canadian mother of two. She was freed unharmed in the northern city of Kaduna late Wednesday. Mulligan was kidnapped while visiting Nigeria with four others as part of a Rotary Club exchange program.

The hostage takers reportedly demanded more than $100,000 for her release. Abductions are common in the restive southern oil-rich Niger Delta, but Mulligan's kidnapping was believed to be the first in the north.

A coalition of 75 rights groups in Northern Nigeria campaigned for the release of the Canadian woman. A spokesman for the group, Shehu Sani, told VOA the kidnapping was "a serious and dangerous development."

"Kidnapping has become a big business for those who partake in it. And it has also enticed a lot of young people from all parts of the country to get involved and abandon whatever they feel they were doing. It is unprecedented in northern part of Nigeria for a foreigner or anyone like that ever to be kidnapped. It's never been part of our culture, it's been part of our history. For a situation like this, it is a serious and dangerous development," he said.

And while Mulligan has regained her freedom, many say Nigeria's booming abduction business will continue. Sani says kidnapping for ransom has become a viable industry in Nigeria. "This trend is not likely to stop because it has reached a point that even criminals that are involved in armed robberies and other violent crimes are seeing the business of kidnappings as the most lucrative. And also it is very clear that many people are benefiting from it," she said.

The Nigerian police chief, Mike Okiro, has said that, between 2006 and 2008, hostage takers extorted more than $100 million from families and oil companies.

Strict new penalties for kidnapping, including the death penalty, are being considered in Nigeria, Africa's top oil producer.

In a report made public earlier this month, a presidential committee on the Niger Delta said 300 people were taken hostage in the troubled southern region in the first nine months of 2008.