By Jeff Chagrin Video producer in Colombia

He is tall and muscular for a Colombian. We shake hands and his grip could splinter granite.

He has a relaxed, easy smile; the type of man who has nothing to prove.

He is 39-year-old Major Luis Ospina, the tactical commander of Colombia's Special Forces (GAULA), an elite police unit tasked with tackling the estimated 8,500 kidnappings in the country every year; the highest figure in the world.

After introductions and pleasantries, there follows a minor bombshell. The major tells me: "I'm very sorry, it is not possible to film us in action."

After a 13-hour flight, it is tempting to mention that Colombia's vice- minister of defence has given me complete carte blanche with this unit. However, I know from past experience that special forces are a law unto themselves. That is what makes them special.

"I've done a lot of work with hostage rescue teams around the world, and they have all heard of you," I tell him. "They were the ones who suggested I come here."

"Really?" the major replies, interested but trying not to show it.

With a night vision camera I sprint madly through the streets of Bogotá

"How about seeing the films I made with these special forces?" I suggest.

He watches my videos and to my delight agrees access on the spot.

Capture

The next day, Major Ospina introduces me to his men in GAULA, many with amusing nicknames such as Roadrunner, Snake Charmer, and my favourite, Mango Pip.

That night I join the major on a sting operation to arrest a suspected extortionist and kidnapper.

A police surveillance team radios the ransom has been picked up and all hell breaks loose. With a night vision camera I sprint madly through the streets, as the major and his men chase the suspect, firing warning shots in the air.

The man is quickly arrested and the money retrieved.

Later, I am invited to the major's house where they are celebrating a family birthday. Like all fighters I have met in Bosnia, Afghanistan, Chechnya and South Africa, once at home, the major changes from hardened warrior to soft and doting father.

After an enthusiastic "Happy Birthday" in Spanish and candle blowing, the major turns to me and tells me sadly: "Our work in Colombia is never ending. Tomorrow, we must begin all over again."

One Day of War was broadcast in the UK on Thursday, 27 May, 2004 at 2100 BST on BBC Two.