Bangladesh has executed two influential opposition leaders on charges of war crimes during the country's 1971 independence war, a senior jail official said, despite concerns that the legal proceedings against them were flawed, and threats of violence by their supporters.

Bangladesh Nationalist Party leader Salahuddin Quader Chowdhury and Ali Ahsan Mohammad Mujahid, secretary general of the main Islamist party Jamaat-e-Islami, were "hanged together, at the same time" at Dhaka Central Jail in the nation's capital, senior jail superintendent Mohammad Jahangir Kabir said.

Security was strengthened near the jail and elsewhere to avoid any violence. A few hours after the execution, a security detail escorted ambulances carrying the men's bodies to their ancestral homes where their families were to perform burial rituals.

The Jamaat-e-Islami party, whose two other senior leaders already have been executed on war crimes charges, issued a statement calling for a nationwide general strike on Monday.

Chowdhury was convicted on charges of torture, rape and genocide during the country's independence war against Pakistan, while Mujahid was found guilty on charges of genocide, conspiracy in killing intellectuals, torture and abduction.

On Wednesday, Bangladesh's Supreme Court upheld their death sentences, and on Saturday, president Mohammad Abdul Hamid rejected a clemency appeal, clearing the way for the executions. The families of Chowdhury and Mujahid met them for the last time inside Dhaka Central Jail on Saturday evening, authorities said.

Jamaat-e-Islami and the Bangladesh Nationalist Party say the trials were politically motivated. Prime minister Sheikh Hasina has denied the allegations. She has acknowledged that she faced international pressure for trying opposition figures for war crimes, but vowed to continue the trials "to ensure justice for the families of the slain people" from the 1971 war.

More than 15 people, mostly leaders of Jamaat-e-Islami, have been convicted of war crimes.

The party had campaigned openly against independence for Bangladesh, which was part of Pakistan until the 1971 war. The Bangladesh government says that Pakistani soldiers, aided by local collaborators, killed three million people and raped 200,000 women during the war.

Mujahid, 67, was the head of Islami Chhatra Sangha, then the student wing of Jamaat-e-Islami . He was accused of being the mastermind behind the killing of intellectuals, including teachers and journalists, days before the Pakistani military surrendered to a joint force of freedom fighters and Indian army units on December 16 1971, after a bloody nine-month war.

Chowdhury, 66, whose father was the speaker of Pakistan's National Assembly and at times, the acting president of Pakistan, also actively opposed Bangladeshi independence. He was accused of carrying out war crimes, including killing more than 200 civilians, mostly minority Hindus, during the independence war, according to evidence presented at the tribunal.

Bangladesh's Mohona TV station said one of its reporters was shot and wounded while covering Chowdhury's funeral.

Rajib Sen was taken to a hospital in Chittagong.