The 60th anniversary of Sri Lanka's independence was marked with more carnage today, when 12 people were killed by a bombing on a crowded bus after a weekend of bloodshed in which at least 29 died in two separate blasts.

In what is suspected to be the latest stage of a separatist campaign by Tamil Tiger rebels, a blast ripped through a bus in the north eastern town of Weli-oya, killing 12 and injuring 17.

Weli-oya is about 120 miles from the capital Colombo, where a female suicide bomber yesterday killed 11 and injured more than 100 when she blew herself up on a crowded station platform.

That attack followed a bus bomb in the central Sri Lankan town of Dambulla on Saturday, which killed at least 18 – most of whom were Buddhist pilgrims – and wounded 50.

The trio of blasts, coming after the Government scrapped a ceasefire with the Tamils last month, mark a dramatic escalation by the Tigers, whose formal name is Liberation Tigers of Tamil Eelam (LTTE).

A wave of violence across Sri Lanka since the truce was dissolved has now killed more than 700 people, including many civilians.

The Sri Lankan armed forces earlier held a defiant show of military prowess to mark independence day, the landmark of its liberation from British colonial rule.

Confirming today's attack, which took place at 3.40 pm local time, military spokesman Brigadier Udaya Nanayakkara said: "The LTTE activated a roadside bomb targeting innocent civilians." The military confirmed that the injured had been rushed to local hospitals.

President Mahinda Rajapaksa, who won an election in 2005 pledging a harder line against the Tigers, accused the group of trying to compensate for the military defeats it has suffered recently in the north and east.

"I call upon the people to remain calm and refuse to be provoked by this repeated brutality by the LTTE, which in its desperation . . . is eager to create a backlash to its terror to obtain the sympathy of the international community."

The Tamil Tigers, which have not commented on any of the recent bombings, usually deny being involved in attacks targeted at civilians.

The Government has pledged to crush the group militarily by the middle of this year. Last month, it drew international criticism by withdrawing from a ceasefire brokered by Norway in 2002 and launching a major offensive against the Tigers in the north.

The Black Tigers

— Tamil Tiger suicide squads, known as the Black Tigers, have carried out more than 240 attacks since 1983

— Many of the suicide bombers are women

— On October 16, 2006, Black Tigers targeted a Sri Lankan naval convoy, killing 93 sailors in one of their bloodiest attacks

Source: Jane’s; globalsecurity.org; Times archive

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