Five men arrested in anti-terrorist raids in southeast England (search) last week were charged Thursday for their alleged involvement in a bomb plot, police said.

Three of the five were charged with possessing 1,300 pounds of a type of fertilizer that can be made into explosives, and suspicion that it was for use in an act of terrorism.

Police released no details of the alleged conspiracy. Two other men who had been arrested in the raids, were released on bail pending further investigation, London's Metropolitan Police (search) said.

More than 700 police officers were involved in the anti-terrorist operation.

Nine people, all of them British citizens, were arrested in London (search) and the surrounding area March 30 and April 1.

One, aged 17, was charged Tuesday with an explosives offense and one was released on bail Wednesday.

The police raids were among the largest anti-terrorist operations in Britain in years, involving five police branches, and resulted in the biggest seizure of potential bomb-making material in England since the Irish Republican Army suspended its campaign of violence in 1997.

The raids spurred intense media speculation about a plot to bomb civilian targets in Britain, although police have released no details of the case against the men.