LONDON, Oct 27 (Reuters) - British prosecutors said on Tuesday they had charged two men under the National Security Act over an incident last month at the RAF Fairford airbase, with police saying the two were suspected of assisting Iran.

RAF Fairford had been used by US bombers to carry out strikes on Iran, but they were withdrawn on security grounds shortly after five British men were arrested outside the military base in southwest England in the early hours of September 27.

The Crown Prosecution Service said it had charged Mohmed Abdulkarim, 24, with engaging in conduct that was likely to materially assist a foreign intelligence service.

Nouman Essghir, 24, was charged with one offence of entering a prohibited place for a purpose prejudicial to the UK on August 22. The pair will appear in court later on Tuesday.

Assistant Commissioner Laurence Taylor, Head of National Counter Terrorism Policing in the UK, said police believed the country Abdulkarim was assisting was Iran.

(Reporting by Sam Tabahriti and Sam Tobin; Editing by Kate Holton)