A security guard after the bombing in Colombo. (Reuters)

Colombo, July 7 (Reuters): Five people were killed and 11 wounded when a suspected Tamil Tiger suicide bomber blew herself up in a police station in the Sri Lankan capital today, shattering more than two years of relative peace.

Police said the woman detonated the bomb as she was being frisked, but the target was government minister Douglas Devananda, a Tamil who is a vocal opponent of the LTTE rebels. The plot was reminiscent of the Rajiv Gandhi assassination.

“A female has gone into the ministry of Douglas Devananda and wanted to meet him... Permission was not granted. People from ministerial security followed her and these officials took her into the police station. While they tried to search her she exploded herself,” said police spokesman Rienzie Perera.

“It is obvious Douglas was the target,” he said. The bomber was among the five dead, police said.

Peace talks to end Sri Lanka’s decades-long civil war have been on hold for more than a year but both sides have been observing a Norwegian-brokered truce signed in February 2002 that put an end to fighting that had killed 64,000.

No one claimed responsibility and the Tigers offered no immediate comment on the blast, which happened on Colombo’s main thoroughfare, near the Prime Minister's official residence and across the road from the US and British embassies.

But police and army officials said they believed the Tigers, who began fighting for a separate state for the island’s minority Tamils in 1983, were responsible. “It is a total violation of the ceasefire agreement. There is not doubt this is the work of the LTTE but we do not yet have proof,” defence secretary Cyril Herath said.

But he said the army would continue to observe the truce.

“The Sri Lankan government has over and over again assured that despite all these provocations they will maintain the ceasefire from their side,” Herath said.

The Tigers terrorised the capital with numerous suicide bomb attacks during the war and on Monday they observed “Black Tiger Day”, which commemorates their suicide bombers.

While they have mostly respected the Norwegian-brokered truce, human rights groups accuse them of targeting rival Tamil politicians, mostly in the island’s east, where a split within the LTTE has complicated the peace bid. Since the split, local media have said, Devananda had been in contact with Karuna, the commander of the renegade rebel faction. The Tigers also accused the army of helping Karuna and his renegades..

Police said apart from the bomber, all four dead were police officers, including two women. Broken glass and blood covered the floor of the police station, which was under heavy guard. “I saw many people being pulled out with injuries, including one with no arm,” said one witness.