Victims of the fire bomb attack are treated in Dhaka Medical Hospital after suffering severe burns
Bangladesh’s opposition leader, Khaleda Zia, has been charged with instigating an arson attack on a bus which claimed the lives of seven people.
Police said the vehicle had been full of sleeping passengers when it was firebombed near the town of Chauddagram on Tuesday.
Ms Zia, the leader of the Bangladesh Nationalist Party (BNP), is one of 56 named people charged over the attack.
The BNP has denied responsibility and condemned the violence.
The attack came in the middle of a general shutdown and blockade declared by Ms Zia last month, which was part of an attempt to force Prime Minister Sheikh Hasina to call fresh elections.
Seven people burned to death and 15 others were injured, as the packed bus travelled from the coastal city of Cox’s Bazar to the capital, Dhaka.
Unlike many vehicles using major roads during the blockade, it had no security escort from police or paramilitary border guards.
Local police chief Uttam Chakrabarty said two cases had been filed, accusing 56 named suspects and another 20 who were unnamed.
Ms Zia has been accused of acting as the instigator.
The main person wanted in connection with the fatal attack is a politician from an Islamist party which works with the BNP.
Nuruzzman Howlader, another police official who filed the cases, said the violence was related to the opposition strike and it was carried out following Ms Zia’s order.
“That’s why her name has been mentioned as the instigator,” he added.
Ms Zia, her aides and opposition activists have all denied involvement in the fire bombing.
The BNP boycotted last year’s election along with other opposition parties, saying it would be rigged.
They were angry that Sheikh Hasina, who has been in power since 2009, refused to stand aside to make way for a neutral caretaker administration to oversee the vote.
Ms Hasina has denounced her opponents as militants and accused activists of engaging in terrorism rather than politics.
She said that if necessary Khaleda Zia would be put on trial for the deaths of people killed in the wave of political violence which started last month.
BBC Bangla’s Sayala Roksana in Dhaka says at least 50 people have been killed and 1,000 injured since 5 January. More than 7,000 opposition activists have been arrested.