We have not given in, and maintain our policy of military offensive

Government security adviser

Millions of dollars of ransom money were reportedly paid to the rebels to secure the release of the hostages, in the Libyan-brokered negotiations.

The Philippine Government had earlier rejected any foreign mediation in the latest hostage crisis, but agreed to Mr Sairin's involvement in a last-minute attempt to postpone Abu Sayyaf threats to behead the American hostages.

Climbdown denial

The government denies that this now amounts to a climbdown.

"We have not given in, and maintain our policy of military offensive" said Philippine Government security adviser, Roilo Golez.

The rebels threatened to behead Martin and Gracia Burnham

Mr Golez said the government had agreed to the involvement of Mr Sairin in negotiations in case he had a "secret formula" for dealing with the rebels.

Mr Sairin is a former member of Malaysia's upper house of parliament, and a local chief in the eastern state of Sabah of the ruling United Malays National Organisation.

He is seen by the Abu Sayyaf rebels as someone who has an understanding of their cause.

Sairin Karno helped to free last year's hostages

Mr Sairin has said he is willing to negotiate but only if his safety is guaranteed by the Philippine Government.

Malaysian officials, meanwhile, have said they are waiting for a formal request from the Philippine Government for the former senator to act as mediator.

Ministers in the Philippine Government are in a difficult position - on the one hand they are pressing ahead with their military offensive and a demand for the unconditional release of the hostages.

But on the other hand they are dealing with a rebel group which has previously had few qualms about carrying out their threats.

Philippine President Gloria Arroyo has warned against giving in again to the Abu Sayyaf demands and has highlighted the dangers of supplying the rebel group with funds to modernise.

However, she and her government are under immense pressure to try to resolve this crisis without any more bloodshed.

It seems that they believed they had little choice but to agree to this one concession.