Bangladesh's parliament has amended a law allowing the state to appeal against the life sentence given to an opposition leader for his role in mass killings and rape during the 1971 war for independence.
Tens of thousands of demonstrators in central Shahbag Square cheered as the assembly approved the changes on Sunday.
Protesters have gathered in central Dhaka for the past 13 days demanding the death penalty for Abdul Quader Mollah, an assistant secretary general of the Jamaat-e-Islami party, for war crimes. The prominent Islamist was given a life sentence by a tribunal last month, stunning many Bangladeshis.
The amendment will "empower the tribunals to try to punish any organisations, including Jamaat-e-Islami, for committing crimes during the country's liberation war in 1971", the law minister, Shafique Ahmed, said
The government is facing growing pressure to ban Jamaat-e-Islami and groups linked to it. Ahmed told reporters the government was considering such a ban.
Lawyers said Sunday's amendment sets a timetable for the government to appeal against Mollah's sentence and secure a retrial. The previous law did not allow state prosecutors to call for a retrial except in the case of acquittals.
The Bangladesh Nationalist party (BNP) of the former prime minister Begum Khaleda Zia and its allies were absent from the vote, having boycotted parliamentary sessions almost since Sheikh Hasina, leader of the Awami League, took office in 2009.
On Sunday, the BNP held a rally outside the party's central office in Dhaka, calling for the next general election, scheduled for next January, to be held under a non-party caretaker administration.
"The government is trying to use the protests over the war crime trials to divert attention from critical national issues such as our demand for election under a caretaker authority to ensure a clean and unbiased vote," the BNP's acting secretary general, Mirza Fakhrul Islam Alamgir, told the rally.
Other BNP leaders urged the demonstrators at Shahbag to speak out against "corruption, politicisation of the administration ahead of the polls and tampering the judiciary to persecute rivals".
Hasina and Khaleda have rotated as prime minister of Bangladesh since 1991 and their unending enmity has led to them being described as the "Battling Begums".
The two are likely to face off again in the next polls, party officials said.
The BNP also accuses Hasina of using the war crimes tribunal as a weapon against her opponents. She denies the accusation.
In its first verdict last month, the tribunal sentenced a former Jamaat leader, Abul Kamal Azad, to death in absentia for killing, murder and torture.
Eight other Jamaat leaders, including its current and former chiefs, are being tried by the war crimes court that Hasina set up in 2010 to investigate abuses during the 1971 conflict. Three million people were killed and thousands of women were raped.
Jamaat activists have called a country-wide strike for Monday, but demonstrators and many shopkeepers have pledged to resist any attempt to enforce such a stoppage.
The authorities deployed paramilitary soldiers in the capital on Sunday evening trying to prevent violence during and ahead of the strike.