The Coalition to Stop the Use of Child Soldiers said the number of conflicts in which children were forced to fight totalled 17 in 2007, down from 27 in its last report in 2004.

The coalition said firm figures were impossible to produce but it was clear there were tens of thousands of child soldiers.

Many were released after a string of wars, particularly in West Africa from Liberia to Sierra Leone. But nine governments kept using children in their armies,it said.

Myanmar -- currently under fire over its human rights record and reluctance to allow in aid workers after a cyclone -- was the most persistent offender, the coalition said.

Children were also used by government forces in Chad, the Democratic Republic of Congo, Somalia and Sudan as well as Uganda and Yemen.

"Child soldiers are ideal because they don't complain, they don't expect to be paid and if you tell them to kill, they kill," the report quoted a senior Chad army officer as saying.

In 14 countries, children were recruited into armed groups linked to the government, for example in Sri Lanka where breakaway ex-Tamil Tigers were seen as government proxies fighting the mainstream rebels.

Most governments accused of using children deny the charge, or say they are aware of it and are trying to stamp it out.

Armed groups in 19 countries or territories used children to fight, the coalition said. Teenagers were used in suicide attacks in Afghanistan, Iraq and the Palestinian territories.

Significant rebel users of child soldiers included Sri Lanka's Tamil Tigers, Uganda's Lord's Resistance Army, Colombia's FARC, Indian Maoists and rebels in Thailand.

Coalition director Victoria Forbes Adam said international laws "have had a limited impact in deterring child soldier use by armed groups".

Rebel commanders in Sierra Leone and Congo are facing war crimes charges over child soldiers but many other alleged recruiters have avoided any penalties.

This month, Britain said it was unlikely to lay war crime charges against former Tamil Tiger commander Karuna Amman, imprisoned for passport fraud and accused by rights groups of widespread child soldier use in eastern Sri Lanka.