Arunachalam Chrishanthakumar, a property valuer and founder of the British Tamil Association, was on Friday convicted of terror charges.
The LTTE is banned in the U.K. as a terrorist organisation.
Chrishanthakumar (52) of South London was convicted of supplying bomb-making equipment to the LTTE and receiving documents for the purpose of terrorism.
But the jury at Kingston Crown Court failed to reach a verdict on three other charges including the allegation that he is a member of the LTTE.
A decision on whether there should be a re-trial is expected to be taken next week.
The court was told that Chrishanthakumar, known as “Shantham”, was warned in 2004 after he bought boots and handcuffs for the LTTE but despite the warning he continued to help it with material some of which had “an obvious terrorist purpose”.
There are an estimated 300,000 Tamils in the UK, a majority of them in London.