The nation is observing the Jail Killing Day on Thursday with due solemnity.

Prime Minister Sheikh Hasina paid tributes to Father of the Nation Bangabandhu Sheikh Mujibur Rahman and four national leaders marking the day.

The day is observed to remember national leaders Syed Nazrul Islam, Tajuddin Ahmed, Captain M Mansur Ali and AHM Quamruzzaman who were assassinated inside Dhaka Central Jail on November 3 in 1975. They played a crucial role in the 1971 War of Liberation of Bangladesh.

The massacre happened barely three months after anti-liberation elements assassinated Bangabandhu and most of his family members on August 15, 1975 at his 32 Dhanmandi residence.

In observance of the day the premier placed wreaths at the portrait of Bangabandhu in front of Bangabandhu Memorial Museum at 32 Dhanmondi here.

Hasina laid wreaths first as the head of the government and then as president of the ruling Awami League early in the morning.

After placing the wreaths, she stood in solemn silence there for some time as a mark of profound respect to the memories of Bangabandhu and the four national leaders.

She was accompanied by by central leaders of the party.

The PM later went to the Banani Graveyard to pay tributes to martyrs of the August 15 and November 3, 1975 massacres.

Different political parties will observe Jail Killing Day, a dark episode in the country's history.

The Awami League and its affiliated organisations hoisted the national flag and the party flag at half-mast. They also wear black badges of mourning.

Meanwhile, President Abdul Hamid and Prime Minister Sheikh Hasina issued separate messages on the occasion.

In a message, the President said: "The aim of the killers was to erase the spirit of the Liberation War from the minds of the young generation apart from giving rise to an undemocratic autocratic rule which failed."

"The nation will always remember the contributions of the four national leaders with due respect."

Prime Minister Sheikh Hasina said: "The killing of the four national leaders was the continuation of the assassination of the Father of the Nation and most of his family. Through it, the defeated forces and anti-state quarters made an evil attempt to destroy the Liberation War spirit and render the Bengali national leaderless by erasing the name of the Awami League."

On November 3, 1975, four national leaders and heroes of the country’s Liberation War -- Syed Nazrul Islam, Tajuddin Ahmad, Captain Mansur Ali and AHM Quamruzzaman -- were assassinated inside the Dhaka Central Jail.

The four leaders played a key role in leading the Mujibnagar government, that led the Liberation War effort in 1971 with Syed Nazrul Islam as the acting president, Tajuddin Ahmad as the prime minister, Mansur Ali as the finance minister and AHM Qamruzzaman as the home, relief and rehabilitation minister.