By Charles Haviland BBC correspondent in Kathmandu

Most of the missing are suspected Maoist rebels

The warnings have been issued on the International Day of the Disappeared.

The London-based Amnesty International said it received reports of 378 people disappearing last year, more than in the previous five years put together.

Nepal has been in the midst of a civil war between the government and Maoist rebels since 1996.

These latest warnings appear to confirm Nepal's unenviable record at the top of the world league for political disappearances.

Amnesty International described what it called a growing culture of impunity in which security forces regularly obstructed investigations into disappearances by the courts and the independent national human rights commission.

It said most cases involved the disappearance of suspected Maoists at the hands of the security forces but it had also had numerous reports of abductions, torture and killings by the rebels.

Alarm

Amnesty's total of 622 people disappeared since 1998 is considerably lower than the figure issued by the national human rights commission itself.

The commission told the BBC it had records of 1,430 disappearances in just three years, more than 1,000 of these at the hands of the government.

The United Nations office here has also expressed alarm, saying that figures for the disappeared were climbing to shocking heights.

The Nepalese Prime Minister recently said the security forces had come under new instructions to respect human rights.