LONDON - Prime Minister Gordon Brown said Wednesday that a Briton held captive in Mali has probably been killed by al Qaeda terrorists.

A statement issued in the name of al Qaeda on an Internet site frequently used for extremist messages said the captive, Edwin Dyer, was killed on Sunday.

Dyer was abducted in January. His captors in Mali had threatened to kill him if Britain refused to release extremist preacher Abu Qatada from prison.

Qatada has been described in Spanish and British courts as a leading al Qaeda figure in Europe.

"We have strong reason to believe that a British citizen, Edwin Dyer, has been murdered by an al Qaeda cell in Mali," Brown said in a statement issued by his office.

"I utterly condemn this appalling and barbaric act of terrorism."

The message posted on the Internet had no video or photo to back the claim and its authenticity could not be independently verified. But the SITE intelligence group, a Washington-based firm that monitors militant messages, also reported the statement on Wednesday.

"This tragedy reinforces our commitment to confront terrorism. It strengthens our determination never to concede to the demands of terrorists, nor to pay ransoms," Brown said.

An email message from Natalie Sarafian, press secretary for Foreign Affairs Minister Lawrence Cannon, says Canada "stands firmly with the government and the people of the United Kingdom in the struggle against international terrorism."

"We express our deepest condolences to the family and friends of Mr. Dyer. Our thoughts and prayers are with them in this difficult time," the email says.

- With files from The Canadian Press