Three men have been arrested by counter-terrorist officers in London and Wales as part of a long-term investigation into the Tamil Tigers.
Scotland Yard said dawn raids took place at residential and business properties in Newtown, Powys, Mitcham, south-west London, and Surrey.
Two men, aged 39 and 46, were arrested at separate addresses in Newtown, and a third, aged 33, was held in Mitcham, a spokesman said.
All three men were arrested on suspicion of the commission, preparation or instigation of acts of terrorism.
They will be questioned later at high security Paddington Green police station in central London.
The spokesman said: "At 6.30am officers from Counter Terrorism Command supported by Dyfed-Powys Police executed search warrants at a number of residential and business addresses in Newtown, Powys. Further warrants were executed at addresses in Mitcham and Surrey. Three men were arrested.
"A 46-year-old and 39-year-old were arrested at separate addresses in Powys and a 33-year-old was arrested in Mitcham on suspicion of the commission, preparation or instigation of acts of terrorism.
"This is part of a long-term investigation into alleged funding and procurement activity in support of terrorism overseas and two people have already been charged in connection with this investigation.
"It is not linked to al Qaida-type activity or inspired terrorism. It is in relation to support, procurement and fundraising for a proscribed organisation, the Liberation Tigers of Tamil Eelam (Tamil Tigers)."
Two men, both from south London, have already appeared in court charged with terrorist offences in connection with the same operation.
