It is a billion-dollar industry: if you are a hostage-taker, this year is turning out to be most profitable.

This month, British aid worker Linda Norgrove was killed when United States forces stormed the camp of the group holding her to ransom.

Last month, eight tourists died during a botched rescue in Manila.

In August, three Russian airmen were kidnapped in Darfur.

In July, four journalists were seized in Mexico. In June, a Russian businessman's granddaughter was taken hostage.

In May, it was Chinese technicians in Nigeria; in April, eight Red Cross workers in the Democratic Republic of Congo.

A ship seized off Somalia was redeemed for US$7 million ($9.37 million), a ransom of US$550,000 was paid for a German banker's wife and, with US$300,000 for an oil worker here and US$10,000 for a shopkeeper's son there, and with governments and insurers making their secret cash drops, it all adds up.

From Mexico City to Mogadishu, the numbers of aid workers, Western staff, tourists and locals taken hostage is rising. In Mexico, more than 7000 were held in 2008 alone, in Nigeria at least 1000 were taken last year and in Somalia foreigners are being kidnapped at a rate of 106 a month.

At least 12,000 people are now taken hostage each year and, this weekend, more than 2000 are enduring yet another day in a makeshift "prison".

Police in Nigeria estimate that ransoms paid there between 2006 and 2008 exceeded US$100 million. Al Qaeda in West Africa alone makes millions taking hostages.

What was once an activity undertaken mainly by insurgents keen to make a political point, or acquire a human bargaining chip, is becoming increasingly commercialised. These days, most hostages are taken for ransom, with sums as high as US$1.6 million paid for their return.

And so a whole industry has sprung up to counteract the criminals: firms offering kidnap and ransom insurance, highly paid negotiators, lawyers, and security personnel.

Criminal "employees" range from teenage hoodlums roaming Sudan to statisticians in London offices keeping check on the going rate for the safe return of, say, a Western oil worker (about US$350,000).

The business' raw material are unprotected people, what have been called "walking gold" - someone in the wrong place at the wrong time who can be taken and converted into serious money.

Public perception is that hostages are mainly people such as Terry Waite (Archbishop of Canterbury's special envoy, held by an Islamic group in Beirut for nearly five years), who are captured to try and force the hand of their government as part of some wider dispute or to publicise the cause of an insurgency.

But the average hostage victim is more likely to be a Mexican seized by a drug cartel or people like Paul and Rachel Chandler, the British couple whose yacht was scooped up by Somalian pirates.

Getting back a hostage is now likely to be a matter for private enterprise. Enough of the hostages work for Western companies - major firms such as Chevron, Adobe and Royal Dutch Shell have all had staff kidnapped - for hostage insurance and its associated trades to have become big business.

Three-quarters of Fortune 500 companies now have kidnap and ransom insurance, and this means that they engage hostage consultants to assess the risk, advise on security, and, if it goes wrong, negotiate with kidnappers, and babysit the family. The premiums paid worldwide for such insurance are now close to US$400 million.

But the huge sums involved in the hostage business make many with a legitimate expertise uneasy.

Although there are worldwide bodies for everything from minor medical conditions to arcane minority sports, not one exists to monitor, study, care for or attempt to release people taken hostage.

Kidnapped and kept for cash
Alan McMenemy

Scottish security guard Alan McMenemy, 34, was abducted in Iraq by a Shiite militant group along with three British security guards and a computer programmer, Peter Moore, more than two-and-a-half years ago. McMenemy is the only one who remains unaccounted for.

Johannes and Sabine Hentschel

Johannes Hentschel, a German engineer, and his wife, Sabine, a nurse, were taken hostage in Yemen in June last year by suspected Shiite rebels with their three young children and four others. The group included a British engineer, Anthony Saunders, two German care workers and a South Korean teacher. Both care workers and the teacher were found dead days later. In May, two of the children were freed by Saudi Arabian special forces. There was no sign of the others.

Stephane Taponier and Herve Ghesquiere

French reporter Herve Ghesquiere and cameraman Stephane Taponier were working in Afghanistan for a French state TV channel when they were seized in December, along with three Afghan colleagues. A recent video shows that the French pair are alive and well. There is no word on their co-workers.