A group of Scotland Yard officers has been suspended after "serious allegations" about their behaviour during the arrests of five suspects last year, police say.

London's police force did not go into detail, but Sky News television, the and of London newspapers reported that six officers were accused of "waterboarding" drug suspects.

The papers gave varying accounts of the exact technique used by police, with saying officers poured water on a cloth and placed it over a suspect's face to simulate the experience of drowning.

The said police officers repeatedly dunked the suspects' heads in buckets of water. The reason for the discrepancy was not immediately clear.

In an email statement, Scotland Yard said that it was "not appropriate to make assumptions" about what the officers did. While a spokesman for the force refused to comment on the nature of the allegations, the statement acknowledged they were grave and "do raise real concern".