He was addressing a regional defence and security conference currently underway in Malaysia, the defence ministry here said.
Dwelling on Sri Lanka's successful counter-terrorism campaign against the banned LTTE which he himself spearheaded, Rajapaksa said much can be learnt from Sri Lanka's experience.
He said a key part of the LTTE's modus operandi was to mobilise support for itself by whipping up ethnic and communal feelings among the Tamil diaspora overseas.
He said the terrorist funds mobilised by groups linked to LTTE is estimated to have been between USD 50 to 75 million on an annual basis from 1993 to 2002, and USD 200 million per annum from 2002 to 2008.
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Rajapaksa said a non-state actor such as the LTTE can mobilise, maintain and successfully utilise a global network to strengthen and sustain terrorist activities in a sovereign nation is a matter of very serious concern both locally and globally.
He charged that some nations seem to have chosen to turn a blind eye to these front organisations and their activities because they claim to support political activism or humanitarian relief.
"At the same time, the network's operatives, most of whom are trained terrorists, remain involved in various illegal activities, and are constantly seeking ways to revive terrorist activities in Sri Lanka."
Last week, Sri Lanka announced the deaths of three key LTTE operatives who were trying to revive the LTTE's armed campaign in the Tamil regions. The government said the three men had been directed by two LTTE leaders based in Europe.
Colombo accuses Tamil diaspora organisations of being behind the third UNHRC resolution in March which prescribed an international probe into the island's human rights record. Sri Lanka has vowed non cooperation with the international investigation.