A series of bombs exploded almost simultaneously in the Bangladesh capital Dhaka, the main port city Chittagong and other towns on Wednesday, injuring at least 20 people and triggering widespread panic.

"We have reports of blasts from different areas and security forces have rushed to the spots. What caused the explosions are yet to be ascertained," a police officer of the Dhaka Metropolitan Police said.

A police officer in Chittagong said they believed the bombs were locally made and remotely controlled. He gave no details.

Authorities said they had immediately tightened security around the country and ordered a crackdown on possible suspects.

Reports from all over the country said the bombs exploded on the streets, at court premises and near key government buildings between 0500 to 0530 GMT.

One bomb also exploded outside Dhaka's Sheraton Hotel, security officers said.

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