LONDON (Reuters) - A 19-year-old man from London has been charged under counter-terrorism law with preparing attacks, the British capital's Metropolitan Police force said on Tuesday.

Haroon Ali-Syed, from Hounslow in the west of the British capital, was arrested last Thursday along with two other men, who have been released on police bail pending further investigation.

The police said Ali-Syed's alleged offence of preparing to commit acts of terrorism took place between April and September this year. They gave no further details. He was due to appear at London's Westminster Magistrates' Court later on Tuesday.

The official security threat level in Britain is currently set at its second-highest category of "severe", meaning that an attack by militants is considered highly likely.

(Reporting by Estelle Shirbon; editing by Michael Holden)