In a report, Christian Aid says conditions in the demobilisation camps are poor with former combatants kept in dangerously overcrowded conditions for a 90-day reintegration period without the training promised for return to civilian life.
Last month, former soldiers and rebels rioted over poor conditions at the Lungi and Port Loko demobilisation camps, near Freetown. Only 1,000 of the 45,000 former combatants have passed out of the DDR process which is underfunded and three months behind schedule, say aid workers.
The British government was a key backer of the Lomé peace agreement in July which set up and funded the demobilisation process. The agreement also gave a controversial total amnesty to Sierra Leone's warring factions, many of them accused of mutilations, rape and major human rights abuses.
Sporadic fighting continues between rebel factions in Sierra Leone's isolated interior and there are widespread reports of robbery, murder and abduction, carried out by roving bands of gunmen and former soldiers, with civilians as their main target.
Speaking from the capital, Freetown, Jenny Borden, Christian Aid's international director said, ""Sierra Leone will not be at peace until the gunmen are disarmed. Time is running out. The international community must help the Government of Sierra Leone to provide an effective demobilisation process that also helps the communities, combatants are returning to. If it fails, the peace process will collapse."
Ms Borden will hand over the Christian Aid report to British High Commissioner, Peter Penfold, in Freetown on Friday 3 December.