At least eight people have been killed and more than 70 injured in a bombing during rush hour on a packed Sri Lankan commuter train, the military says.
The blast hit the Colombo-Panadura train in Dehiwala station, in a suburb of the capital, Colombo.
Many of the dead were women, including one who was pregnant.
Military spokesman Brigadier Udaya Nanayakkara blamed Tamil Tiger separatists for the attack, the latest in a string targeting public transport.
The military says it defused two bombs found on buses over the weekend.
Tamil Tiger separatists are regularly blamed for attacks, although they routinely deny involvement in bombings in the country.
Monday's blast comes three days after the rebels blamed government forces for an explosion which killed a group of people in Tiger-controlled territory.
Toll 'could rise'
The army said Monday's explosion occurred at 1650 local time (1120 GMT).
Bodies were pulled from the wreckage and the defence ministry said the number of dead could rise.
Commuter Ramani Padmalatha, 42, told French news agency AFP that the train suddenly slowed after a "deafening noise".
"People were shouting 'bomb, bomb!' and scrambling to get out of the windows of the carriage... I managed to jump out from the door. People were stumbling out of that carriage with blood stains on their clothes, some with burns, some looking dazed," she said.
Eyewitness R A Upali told the BBC Sinhala service the explosion took place as the train was pulling out of the station.
"I ran to the place where the explosion happened. I saw people fall on the platform. People with minor injuries ran towards us."
The train compartment's windows were blown out and part of its roof was torn off in the blast, which left bloodstained bags and umbrellas strewn among the debris.
Victims of Sri Lankan train bomb are treated in hospital
The attack came ten days after a suicide bomber on a motorcycle rammed a bus carrying police officers, while an explosion last month inside a bus killed more than 20 people.
In February, 11 people died in a suicide attack at Colombo's main train station.
Meanwhile, battles have been continuing in the north of Sri Lanka, where the military is carrying out an offensive aimed at crushing the rebels by the end of this year.
On Monday air force helicopters attacked Tiger positions a day after fighting on the ground killed 21 rebels and one soldier, according to the military.
Correspondents say that the number of attacks in the south has increased as the fighting has intensified in the north.
The Tigers have fought for a generation for an independent state for the Tamil minority in the island's north and east.
About 70,000 people have been killed since the civil war began in 1983.
Violence in the island nation increased after the government formally pulled out of a ceasefire agreement in January.
Before the latest outbreak of hostilities, the Tamil Tigers had warned that not only the Tamils in the north, but the majority-Sinhalese in the south would also feel the impact of the war.
The warning has been followed up by roadside bombs, suicide blasts and explosions targeting public transport in the south, although civilians inside rebel-held territory in the north have also become victims of mines allegedly planted by the army.
Analysts say that if the violence continues, the government may be forced to redeploy some troops from the northern battlefront to the south to step up security.
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