Clashes erupted in Bangladesh on Wednesday after the execution of a top political leader, heightening tension in a country reeling from a string of killings of secular and liberal activists.

Motiur Rahman Nizami, leader of the Jamaat-i-Islami (JI), was hanged at a Dhaka jail late Tuesday for 'the massacre of intellectuals during the 1971 war'.

Police said they fired rubber bullets after hundreds of Nizami's supporters attacked them with stones in the northwestern city of Rajshahi.

“There were 500 Jamaat activists who were protesting the execution. We fired rubber bullets as they became violent,” Rajshahi police inspector Selim Badsah told AFP, adding that about 20 were arrested.

Jamaat and ruling party supporters also clashed in Chittagong, where about 2,500 men attended a service for the executed leader, the port city's deputy police chief Masudul Hasan told AFP.

Security was tight across the country, with checkpoints erected on main roads in Dhaka to deter violence, and thousands of police patrolling the capital.

Nizami, a 73-year-old former government minister, was the fifth and the most senior opposition figure executed since the Hasina Wajid government set up a controversial war crimes tribunal.

Security was also stepped up in Nizami's ancestral district of Pabna, where his body was taken under armed escort for burial in his family's grave.

“At least 16 activists of Jamaat were arrested (in Pabna) on Tuesday night as part of the security clampdown,” local police inspector Ahsanul Haq said.

Jamaat called a nationwide strike for Thursday in protest at Nizami's execution, saying the charges against him were false and aimed at eliminating the party's leadership.

Executions of Jamaat officials in 2013 triggered the country's deadliest violence in decades. Around 500 people were killed, mainly in clashes between JI men and police.

But a fresh wave of bloodshed is considered unlikely following a major crackdown by Prime Minister Sheikh Hasina's government that has seen tens of thousands of Jamaat supporters detained.