The Sri Lankan military said on Saturday that an explosion rocked the capital Colombo.
The military official, who spoke on condition of anonymity citing government policy, said details on casualties were not immediately available.
Hospital spokeswoman Pushpa Soyza said 44 wounded people were receiving treatment after Saturday's blast.
Sri Lanka is immersed in a decades-long civil war.
The Tamil Tiger rebels have fought for an independent state in the north and east since 1983, following decades of marginalization of ethnic Tamils by governments dominated by the Sinhalese majority.
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