ADDIS ABABA - Twenty-five African states agreed Friday to step up efforts to regulate mercenary activity on the continent amid an explosion of private security companies on the continent.

The nations decided at the end of a two-day meeting with a UN working group in the Ethiopian capital, Addis Ababa, to propose regulations at the September meeting of the UN Human Rights Council, participants said.

"Clearly a consensus has emerged, a willingness of the participating states to regulate more the activities of the PMSCs (private military and security companies)," one delegate told AFP.

Jose Luis Gomez del Prado, from the UN committee on mercenaries, told the meeting the largely U.S.- and British-based industry, worth many billions of dollars a year, had boomed in African and across the world.

"With the wars in Afghanistan and Iraq, we have seen this embryonic industry explode. There is a new dimension with the piracy in Somalia," he said.

Private security "multinationals", 70-80 per cent of which were based in the United States or Britain, were recruiting around the world, he said, adding there was an "osmosis" between these groups and typical mercenaries.

"This market represents between 20 and 100 billion dollars a year," Del Prado said, adding that these guns for hire posed a "great danger" to fragile governments.

In Africa there was "resentment towards private armies mainly because of the involvement of mercenaries in regime change in a number of African countries," said African Union security expert Norman Lambo.

In one example, British-led mercenaries led a foiled coup in 2004 against the government of oil-rich Equatorial Guinea.

"It is unfortunate that of late some groups have decided to move their mercenary activities to hide them under private security activities," he told the meeting.

Nine African states are among 32 countries that have ratified a 1989 UN Convention against the recruitment, use, financing and training of mercenaries.

The Organization of African Unity, predecessor of the African Union, adopted in 1977 a convention on the elimination of mercenaries which was in turn adopted by 30 African countries.

However there were a number of loopholes in the document and it needed to be strengthened, del Prado said.

The head of the UN group, Shaista Shameem, said the current regulations were "largely inadequate".

"Africa is also becoming an important market for the security industry as well as a supplier of personnel for the industry."

"This new phenomenon is largely unregulated and has led to a situation which has impacted negatively on human rights," she said, adding that these groups were "rarely held accountable" of they committed abuses.