The Sri Lankan government has warned the public to remain vigilant after two bomb blasts killed at least 23 people and injured about 100 others.
The first attack happened during morning rush hour in the capital Colombo.
A remote control device exploded as a crowed bus passed by.
Witnesses say the vehicle was shredded by shrapnel and the floor was covered in blood.
A second explosion, which also destroyed a bus, happened a few hours later near the town of Kandy
The armed separatist group the Tamil Tigers which is fighting for an independent state, is being blamed by the authorities.
The blasts are the latest in a series of assaults by suspected rebels on the country’s transport system.
They follow accusations by the Tamil Tigers that the Sri Lankan military are behind several roadside bombing which have killed civilians in the country’s rebel-held north.