An American missionary couple held hostage in the southern Philippines have begun their second year in captivity with no sign of being freed soon.

Martin and Gracia Burnham were kidnapped a year ago by Abu Sayyaf guerrillas.

The group is best known for kidnapping for ransom although the US has linked it to Osama Bin Laden's al-Qaeda network.

Every time I hear a twig snap, I think it's a gunshot

Gracia Burnham, November 2001

US troops have for several months been helping train local soldiers to fight the Abu Sayyaf but there has been no progress in rescuing the hostages.

Martin Burnham's father last month said his family recently paid a ransom to the rebels but that the rebels reneged on the deal.

The Philippine authorities have denied any deal was made. The government has always refused to negotiate for the release of the Burnhams, who are being held in the jungles of Basilan island along with a Filipino nurse, Ediborah Yap.

Jungle survival

The Americans were snatched from a luxury resort on 27 May last year, where they were celebrating their 18th wedding anniversary. Dozens of people were captured with them and in a series of raids that followed.

Some have been killed, including an American man captured with the Burnhams, but most were released for ransom.

There have been a number of reported sightings of the Burnhams but unmanned spy planes, thermal imaging cameras and other high tech equipment have all failed to find them.

The Burnhams mostly eat root crops, bananas and an occasional rice or chicken meal. They are forced to hike through jungles for hours as their captors evade troops.

Threat

In a video taken in November, Martin said he and Gracia shared a hammock but "each night I am chained to a tree by my left wrist".

Chronology

27 May 01: Burnhams seized from Dos Palmas island resort and taken to Basilan Sep 01: The US puts Abu Sayyaf on terror blacklist Jan 02: US military advisors arrive in Philippines May 02: Reports that Burnhams are in ill health

"Every time I hear a twig snap, I think it's a gunshot," Gracia said as her husband stood beside her.

Both looked in poor health and there were reports earlier this month that Martin Burnham was suffering from malaria.

Also this month the kidnappers said they were no longer prepared to negotiate over the hostages and threatened to kill them if troops got too close.

The Burnhams are from Wichita, Kansas, but have lived in the Philippines for about 15 years.

They are the longest-held foreign captives in the Philippines since Muslim separatists began seizing hostages in the 1970s to press for an Islamic state in the south of the mainly Catholic country.