By Justin Pearce BBC Luanda reporter

When I first saw Carlos, I assumed he was a child playing around by dressing up in his father's military uniform.

As we talked, I realised he was a real soldier who had fought his first battle aged 13.

I saw people killed, injured

Carlos

"I'm 15," he said. "I've been in the Angolan Armed Forces since 2000."

I met Carlos in Cuemba - a tiny town in central Angola which is home to a large garrison, in the middle of an area which has been hotly contested by the Angolan Armed Forces and the Unita rebels over the last few years.

The town was off-limits to outsiders until a few weeks ago, when humanitarian assistance started arriving following the cease-fire signed on 4 April.

Carlos said that in the year 2000 he had fought in the battle of Lungue Bungo - a battle that took place in the eastern Angolan province of Moxico when Carlos would have been only 13 years old.

Uncertain future

"Were you frightened?" I asked.

"Yes, I was."

"What happened in the battle?"

"I saw people killed, injured."

Carlos shows no obvious signs of being traumatised by his experiences.

Carlos would like to go back to school

He seemed to get on well with other soldiers - who appeared to be in their late teens or early twenties - as well as with other civilian children in the town.

They played together on the rusting hulk of an old tank, climbing and swinging on the barrel of its gun.

When I asked Carlos what he wanted to do in the future, he seemed uncertain.

He said he wanted to remain in the army, but also said he wanted to study in the second grade.

He said he had already had some education, and could read.

"Do you think that it's right that children should become soldiers?" I asked.

He paused.

"I don't know. That's war."

Our conversation had to end there, as some older officers approached, concerned about Carlos talking to strangers.

The following day, we were taken to visit the local military base - the headquarters of the Angolan Armed Forces 20th battalion.

There I noticed at least two other boys in military uniform who looked no older than Carlos.