(CNSNews.com) -Muslim separatists holding 21 hostages in the Philippines clashed with government forces Tuesday, shortly after a man claiming to represent the group threatened to start beheading the captives. Ten of the captives are foreign tourists.
Reports from the southern Philippines say casualties were sustained on both sides, although the gunfight was described as limited.
Members of the Abu Sayyaf terrorist group are holding the 21 on a remote island called Jolo while negotiations continue with government representatives.
The hostages were seized from a beach resort in nearby Malaysia on Easter Sunday. They include 10 Malaysian workers, a Filipino, and tourists from Germany, France, South Africa, Finland and Lebanon.
Abu Sayyaf, a group the U.S. believes has links to the wanted terror chief Osama bin Laden, is fighting for an independent Islamic state in the mostly Roman Catholic Philippines.
It has demanded a $2.4 million ransom for the hostages' safe release.
Several thousand troops are surrounding the camp where the hostages are being held. A local radio station was called Tuesday by a man claiming to be one of the hostage-takers, who warned two of the foreigners would be decapitated unless the troops were moved back.
The group also warned it would seize more hostages.
It was the second time the beheading threat was made. Late last week a man speaking for the group said it would execute two hostages in this manner unless the government replaced an envoy it had sent to negotiate with them.
The negotiator, Nur Misauri, is the former leader of another Muslim separatist movement, which signed a peace accord with the government in 1996.
According to Philippines press reports, Misauri has subsequently been accepted as a negotiator.
The Manila Bulletin daily said Tuesday that after opening formal negotiations with the rebels, Misauri expressed optimism that they would release their prisoners unconditionally, without payment of ransom.
Filipino journalists who have been allowed access to the hostages say they are looking ill and weak, but say they are not being mistreated. They pleaded for their freedom.
Another Abu Sayyaf unit is currently embroiled in a separate hostage situation. It has been holding 27 Filipino hostages, mostly Catholic schoolchildren, on another southern island since March 20, demanding freedom for three Islamic militants imprisoned in the United States for terrorism.
The stronghold where the 27 were being held was overrun by government forces after a bloody gun battle on Sunday, but surviving militants reportedly escaped with their captives. Some reports suggest they may have been taken to Jolo island too.