Three others Shamsher Singh, Lakhwinder Singh and Gurmeet Singh were handed out life imprisonment by the court of R K Sondhi held inside the high security Burail Jail in Chandigarh.
Naseeb Singh was given 10 years imprisonment which he has already undergone during the trial spanning over 11 years.
The court had on Monday reserved its verdict on the pronouncement of quantum of sentence to the six convicts in the case after hearing the argument of CBI and the defence lawyers.
Jagtar Singh Hawara, Balwant Singh, Shamsher Singh, Lakhwinder Singh and Gurmeet Singh were convicted under Sections 302 (murder), 307 (attempt to murder) and 120 B (criminal conspiracy) of the IPC while Naseeb Singh was held guilty under the Explosives Substances Act.
The seventh accused Navjot Singh was acquitted by the special court.
Two other accused Jagtar Singh Tara and Paramjit Singh Bheora had escaped from the Burail Jail alongwith Hawara, who was later re-arrested.
Three others named in the case Mahal Singh, Wadhawa Singh and Jagroop Singh are absconding while three NRIs Manjinder Singh Grewal (England), Resham Singh (Germany) and Harjit Singh (USA) were declared Proclaimed Offenders (POs) on February 19, 1996.
A total of 15 persons had been named as accused in the charge-sheet besides the human bomb Dilawar Singh, who died in the blast at the entrance of the 10 storeyed Punjab and Haryana Civil Secretariat in Chandigarh.
Hawara and Balwant Singh raised pro-Khalistan slogans inside the court as soon as the Judge announced sentence, Defence Counsel Amarjit Singh Chahal told repoters outside the jail.
Media was not allowed entry inside the Jail to cover the court proceedings.
Chahal said that both Hawara and Balwant accepted the verdict. Balwant also announced that he would not go in for an appeal, Chahal added.