By Keith Somerville BBC News Online

Coups, civil wars and military conflict have been a sad fact of life for millions of Africans for the past four decades.

Most of these wars have been home-grown or were the product of flaws left behind by nearly a century of colonial rule.

One thing practically all of them have in common is the role of foreign mercenaries or accusations that one or more of the combatants used mercenaries against their enemies.

Military conflicts have plagued Africa

Mercenaries started operating in African conflicts within a few years of the start of the era of independence in the 1960s.

Former soldiers from the colonial powers were back in Africa as paid killers for governments, rebel movements or even European commercial companies involved in conflict areas.

Call them "dogs of war" or "soldiers of fortune", they have been an ever-present factor in Africa's conflicts from the Congo war of the early 1960s to the most recent conflicts.

As recently as October, allAfrica.com reported that former rebel soldiers from Sierra Leone and Liberia were trying to make their way to Ivory Coast to sell their services.

There have also been unconfirmed reports of South African and French mercenaries being employed by the Ivorian Government to support their fight against the rebels.

Out of control

Mercenaries like Bob Denard, Mike Hoare and Jacques Schramme became notorious in the 1960s for their role in the Congo.

And their names just kept cropping up in Africa's conflicts.

Bob Denard has been involved in wars in Congo, Angola, Biafra and the Comoros, to name but a few.

We are established entities, have established sets of principles and employ professional people

Michael Grunberg Sandline

The image of the mercenary was of a former European or American regular soldier who then made a living selling his ability to kill or to command others to kill to anyone who had the money but not the expertise to fight a war.

They were accused of atrocities, of fuelling conflicts and of being beyond anyone's control.

African politicians condemned their presence in Africa, but African presidents or rebel leaders still employed them.

European or American politicians called for curbs on their activities, but the CIA hired mercenaries for use in the Congo and Angola.

In the 1970s, British mercenaries were involved in the start of the civil war in Angola - several of them being captured, tried and executed by the Angolan Government.

Private military companies

And mercenaries still exist and, it seems, prosper in Africa.

One military source who wanted to remain anonymous, told BBC News Online that mercenaries were still very active and could command $10-20,000 a month for their services.

The DR Congo war involved many armed groups including mercenaries

And there has also been an increase in the involvement of states in African conflicts for commercial reasons.

A recent UN report detailed the way in which senior military and political figures in Rwanda, Uganda and Zimbabwe were involved in the exploitation of the country's natural resources during their countries' involvement role in the conflict in the Democratic Republic of Congo.

The involvement of their political or military leaders in looting resources was rejected by Rwanda, Uganda and Zimbabwe.

Libya was reportedly granted mining rights in return for supporting the government of the Central African Republic.

But the major development in outside involvement in conflicts for profit in recent years has been the appearance of private military companies which offer their services to governments and to commercial companies.

The best known of these was Executive Outcomes (EO) - initially based in South Africa and involved in Angola and Sierra Leone.

In Angola, EO employed former South African soldiers and was paid by the Angolan state oil company, Sonangol, to assist the Angolan army in regaining control of the Soyo oilfields from Unita rebels.

The company was also contracted to train Angolan troops and direct some of their operations against Unita.

In a report on private military companies released in February, the British Foreign Office estimated that EO was paid $40m for its services.

The same company was later involved in supporting the Sierra Leone Government in its attempts to defeat rebels.

The British-based company Sandline also helped Sierra fight the Revolutionary United Front rebels.

Commercial reputation

Michael Grunberg, a commercial adviser for Sandline, told BBC News Online that private military companies like Sandline see themselves as different from the old image of mercenaries.

"We are established entities, have established sets of principles and employ professional people."

He said Sandline operated as a commercial company and wanted to have a reputation that would enhance its business position.

He emphasised that it would not accept contracts from groups or even governments that would risk damaging its commercial reputation.

Peacekeeping and the dogs of war

A decade ago, Western governments publicly condemned mercenaries, even if they might have been willing to use them covertly.

The rise of the private military company is beginning to change attitudes towards paying non-state military organisations to carry out activities once regarded as the preserve of the state.

Private military companies could become involved in peacekeeping

The British Foreign Office report on private military companies noted that the demand for military services from the UN and international organisations could mean that it would be cheaper to employ private military companies to perform these tasks than to use troops from members states.

In his preface to the report, British Foreign Secretary Jack Straw differentiated between "mercenaries of the rather unsavoury kind" and reputable private military companies.

While saying that a wider debate was necessary, Mr Straw said that it was worth considering the licensing of private military companies to encourage reputable ones and eliminate disreputable operators.

Even the UN Secretary General, Kofi Annan, is said to have considered the use of private companies to support UN operations, but to have decided that the time is not right to move in that direction.

Already, private security companies provide guards for international organisations and aid groups working in conflict zones.

So it is clearly not beyond the realms of possibility that the dogs of war could end up being employed on peacekeeping missions.