Palestinian forces could take military action to release kidnapped British journalist Alan Johnston, a close adviser to President Mahmoud Abbas said.
The first video of the BBC reporter since his abduction two and a half months ago was broadcast on a militant website on Friday by his self-proclaimed kidnappers, calling themselves the Army of Islam.
Mr Abbas' adviser Saeb Erekat said that the Palestinian Authority knew nothing about the so-called Army or its alleged leaders in the Dugmush clan. But he said that all sides of Palestinian political life were united in their determination to secure Mr Johnston's release.
Mr Erekat told the BBC: "Fatah, Hamas, all the factions, the President, the Prime Minister, in this particular case, they see eye to eye. We are all unified as far as condemning this despicable and shameful act.
"We must really determine where his location is, and then move... even if it takes a military or a security operation."
Mr Erekat said the video amounted to a "proof of life", but added that it was clear the journalist was speaking under duress.
Asked about the Army of Islam, he said: "These people are nothing more than gangsters. I don't think they are linked to anyone."
Mr Johnston's family yesterday said they were "buoyed up" after seeing the video containing the first images of him since he was captured in Gaza City on March 12.
Johnston, 45, from Argyllshire, was pictured from the waist up wearing a red sweatshirt and appeared calm as he delivered a statement lasting around five minutes to the camera.
The Foreign Office condemned the video's release, which it said could only add to the distress of the reporter's family and friends. And Prime Minister Tony Blair and his anointed successor Gordon Brown both came forward to call for the reporter to be freed immediately.
