Five men have been arrested in Dover and east London by anti-terrorism police.
Scotland Yard said two of the five were arrested as they tried to board a boat at Dover port on Sunday.
Two others were arrested in east London in the early hours of Friday morning and the fifth had been apprehended in Dover at about 8.30am on Friday.
The BBC has reported that the offences are thought to relate to Syria and not to plans for an attack in the UK.
All the suspects are all being held in central London police stations.
