A Tamil Tiger suicide bomber triggered a blast inside offices of the main opposition party in northern Sri Lanka on Monday, killing at least 27 people, including a senior retired general, officials said.
  
The attack in the town of Anuradhapura came as the Sri Lankan military appeared on the verge of capturing the Tigers' key northern headquarters as part of a major offensive in the drawn-out ethnic conflict.
  
"The LTTE (Liberation Tigers of Tamil Eelam) set off a suicide explosion. There are a large number of casualties. At least 27 are dead and 80 injured," said military spokesman Brigadier Udaya Nanayakkara.
  
The blast killed retired army general Janaka Perera, the local head of the United National Party, who was attending a ceremony to open the offices when the attack occurred. It was unclear whether he was directly targeted.
  
Perera, whose wife was also killed, was a war veteran credited with some of the army's biggest victories over the Tigers, including a 1996 battle in which 200 rebels were killed with the loss of just one soldier.
  
The United National Party (UNP) officially support a negotiated settlement with the Tigers and say the current offensive is being used by the government for political ends.
  
The UNP's Ranil Wickremesinghe was prime minister in February 2002 when Colombo and Tiger rebels negotiated their Norwegian-brokered peace deal, which finally collapsed earlier this year.
  
Sri Lanka's army chief said at the weekend that his troops were on the verge of capturing the northern rebel headquarters in Kilinochchi.
  
Army forces had advanced to within two kilometres (1.25 miles) of the stronghold, Lieutenant General Sarath Fonseka said in a speech.
  
Wresting control of Kilinochchi would be a major blow to the Tigers, who took up arms in 1972, demanding minority rights, and in 1976 raised the demand for a separate state called Eelam.
  
As the political capital of the LTTE's northern mini-state, Kilinochchi is where the rebels have hosted visiting foreign dignitaries and peace brokers.
  
The Tigers, who are known for their trademark suicide attacks, have put up only intermittent resistance to the military forces advancing on several fronts in the north of Sri Lanka.
  
But defence analysts recently warned that the Tigers still had suicide attackers who could be deployed with devastating effect.
  
"(The) Tigers could be facing the biggest defeat since 1995, but you can't ignore their ability to carry out suicide attacks," one analyst, who declined to be named, told AFP at the weekend.
  
Foreign aid workers who evacuated the northern region three weeks ago said most residents of Kilinochchi had fled as the fighting moved closer.
  
Fighting across the northern frontier on Saturday left at least 25 Tigers and five soldiers dead, the defence ministry said Sunday.
  
The Colombo government formally revoked a moribund truce in January and since then, 7,183 Tigers have been killed, according to the military, which places its own losses at 702 soldiers.
  
The casualty figures cannot be independently verified.