The Philippine coastguard has confirmed that a suspected member of a militant Muslim group was aboard a ferry that caught fire last week.
Witnesses said they heard an explosion before the fire
Coastguard Rear Admiral Arthur Gosingan said Arnulfo Alvardo was on the ship's manifest and was one of the 133 passengers still missing.
On Sunday the Abu Sayyaf group said it was behind the incident and named Mr Alvardo as the suicide bomber.
The government dismissed the group's claim as a "propaganda ploy".
Rear Admiral Gosingan denied that the discovery of Mr Alvardo's name meant that Abu Sayyaf was involved in the incident.
"They could have just said anyone on the list of missing is one of their members," he said.
He had earlier said Mr Alvardo was not on the passenger list.
President Gloria Arroyo has also continued to dismiss the Abu Sayyaf's claims.
"The truth behind this incident is emerging; no terrorists, no missing bodies," she said in a statement.
The 10,000-ton Superferry 14 was heading for Bacolod in the central Philippines when it caught fire on Friday.
Around 700 of the 899 passengers were rescued.
Only one person has been confirmed dead according to the coastguard and the ferry operator. The rest are missing.
Witnesses reported a powerful blast had triggered the fire but one official said the investigators had "found no trace of explosion".
The search for survivors is still continuing.
The authorities are optimistic that most of the 133 people still missing had already been rescued by smaller vessels and had merely failed to report in.
President Arroyo said the rescue operation will continue "until we are sure that there are no more bodies inside the ill-fated passenger ship".
The ferry fire broke out on the same day that a court sentenced two Abu Sayyaf members to life imprisonment for kidnapping.
The group - which mainly engages in kidnap for ransom - is one of four Muslim rebel groups operating in the southern Philippines.
It has been labelled a terrorist organisation by both Manila and Washington, and is believed by the US to have links with Osama Bin Laden's al-Qaeda network.
The Philippine Government has deployed thousands of troops in the south in an effort to rescue the last of the hostages and eradicate the Abu Sayyaf.