Washington ? U.S. officials were investigating international media reports Friday that Kansas missionary Martin Burnham, who is being held hostage in the Philippines by a Muslim extremist group, has steadily worsening malaria and could die without proper treatment.

Oreta Burnham, Martin’s mother, said the State Department was following up reports by French, German and British news services quoting Philippine Col. Alexander Aleo as saying that Martin Burnham has suffered from malaria for the past several weeks and that lack of rest is making his condition worse.

“We are receiving information that Martin Burnham is sick and suffering from malaria,” Aleo told the British Broadcasting Corp. “The Abu Sayyaf holding Martin is worried that he might die an untimely death.”

Aleo, who commands a Philippine brigade pursuing the kidnappers of Martin and Gracia Burnham on the southern island of Basilan, added that the military is prepared to give Burnham the medicine he needs once he’s found.

The Rose Hill, Kan., missionary couple have been held hostage in the Philippines since May 27, 2001. But despite the presence of about 7,000 Filipino and 1,000 U.S. soldiers, the small band of Abu Sayyaf kidnappers holding the Burnhams and Filipino nurse Deborah Yap has eluded capture.

Hopes of the Burnhams’ release have risen and fallen in recent months. An attempt to pay a $300,000 ransom for their release failed in March. Late last month, Abu Sabaya, the group’s spokesman, suggested the Burnhams would be executed because of the Philippine government’s refusal to negotiate their release.

Malaria is common in the southern Philippines, where Martin and Gracia are. The disease is carried by mosquitoes in tropical climates.