British police charged a fourth man Monday in connection with alleged threats to assassinate Prime Minister Gordon Brown.

Lancashire Constabulary said in a statement that 24-year-old Muhammad Ali Mumtaz Ahmad was charged with possessing an item suspected of being useful for the preparation or instigation of an act of terrorism.

A police spokeswoman said the charges relate to the alleged threat to kill the prime minister. She spoke anonymously in line with force policy.

Media reports said the men were being held in connection with a Web site posting signed "al-Qaida in Britain" that threatened the life of Brown and his predecessor Tony Blair. The statement, posted on a radical Web site earlier this year, demanded the withdrawal of British troops from Iraq and Afghanistan, and the release of some Muslim inmates from Britain's high-security Belmarsh prison.

Police arrested two of the men, Ishaq Kanmi and Abbas Iqbal, on Aug. 14 at Manchester Airport in northern England, reportedly as they were about to board a flight to Finland. The men and Iqbal's brother Ilya Iqbal — arrested in Accrington 35 miles (56 kilometers) north of the airport — were charged with terror offenses related to the same case last week.

The men were described by police as being Asian, which in a British context suggests they are of Indian, Pakistani or Bangladeshi descent.

Ahmad and the other charged men are from the northern English city of Blackburn.

Greater Manchester Police on Monday were granted a warrant for further detention to question a fifth man arrested on Aug. 26 in the central English town of Derby.

Ahmad will appear at Westminster Magistrates Court Tuesday.