By Justin Pearce BBC, Capembe, Angola

On the riverbank at Capembe, in south-eastern Angola, men with pickaxes are hacking away at the grey mud.

I found a diamond, it's at home. I'm going to sell it

Child in Capembe

Somewhere amid these tons of earth there may be a diamond or two.

This kind of diamond prospecting is known in Angola as "garimpo", and the people who do it are called "garimpeiros".

Capembe is a reception centre for former Unita soldiers, and the now demobilised rebel fighters are carrying on a trade which once bankrolled their war.

Children

One of the men, Fernando Jose Palanca, has been a garimpeiro for two years.

"I've searched for diamonds in Mavinga, in Matungo and now here in Capembe. I've found two stones here, but I haven't sold them yet," he says.

"There are traders here, in the reception area - they go around and we can sell to them. They have their networks, they can contact people in other countries who need the diamonds."

The soil that the men dig up from the river bed is washed to separate the sand from the gravel, then the gravel is sifted into stones of different sizes.

At this stage you can start looking out for diamonds in the bucketful of stones, and often it is the sharp eyes of children who do the looking.

"I found a diamond, it's at home. I'm going to sell it," says a child.

It is uncertain how many houses in the reception centres have diamonds hidden away somewhere.

Unita

General Kamorteiro, the former chief of Unita's armed forces and now deputy commander-in-chief of the Angolan armed forces, recently warned that the days were numbered for ex-Unita soldiers still digging for diamonds.

Former Unita soldiers went to demobilisation camps in April

But the officer in charge of the Capembe reception area, Colonel Raoul de Almeida, confirms that the garimpeiros here are indeed former Unita fighters.

"The garimpeiros are people from here, from the reception area. They are excavating, trying to make up for lost time," he says.

"They are not yet selling diamonds, just digging, but if someone came along, they might sell," the colonel says.

Regulations

In an attempt to bring the informal diamond trade under control, the government three years ago established Ascorp, a company in which the state has a majority share, and which has a legally enforced monopoly on all diamond sales in Angola.

When I ask the colonel if Ascorp has arrived, it seems as if he had never heard of the corporation.

"No, no, Ascorp is not here," he says.

Justino Andre has been digging diamonds ever since the days when Unita officers used to sell the stones across the border in Zambia.

Government regulations are not yet in force here

Despite the pressure of international sanctions, this trade continued to finance Unita's military operations right up until the end of the war.

I ask if Unita is still in control of the trade.

"At the moment - in this area it is mainly Unita that's in control. But there is no officer who is in control of the trade. I can't say exactly who is receiving money, but the trade is free," Mr Andre says.

Unita's structures have collapsed, yet the government's own regulations have not yet reached this remote corner of the country.

And the garimpeiros are taking advantage of the free-for-all while they can.