Colombo: A powerful bomb damaged a 330,000 KW electricity substation near the Sri Lankan capital early on Wednesday, another indication that terrorism is taking a new form with Tamil Tigers hitting soft economic targets to disrupt life in the island country.

"The equipment was repaired but for half an hour the area was in darkness," military spokesperson Brigadier Udaya Nanayakkara said after the blast at Arachchikottuwa near Chilaw, north of Colombo.

There are some 5,000 business establishments and 20 prawn farms in the area.

On Tuesday, people found a device packed with four kg of the deadly C4 explosives near an electricity transformer in Puttalam, north of Colombo. The bomb squad defused it.

"These are scare bombs which the LTTE (Liberation Tigers of Tamil Eelam) plants in various civilian areas to spread panic among the public," Nanayakkara said.

The London-based Amnesty International condemned the Tamil Tiger bomb attacks on civilians and the Sri Lankan army's "indiscriminate" attacks in offensives in Tamil-speaking north Sri Lanka.

It pointed out that 34 people, mostly civilians, had been killed in bomb blasts in three places in Sri Lanka since Jan 29.

"Both the Sri Lankan government and the LTTE are failing to comply with their obligations under international humanitarian law and are killing civilians on an increasingly regular basis.

"With no perpetrators brought to justice, a climate of impunity is becoming entrenched: unless these patterns are reversed the future appears bleak," said Tim Parrit, Amnesty's deputy programme director for Asia-Pacific.

Source : IANS