The leader of Sri Lanka's Catholics demanded that the government find the perpetrators of deadly Easter attacks two years ago, as black-clad worshippers held silent protests outside the capital's churches on Sunday.
No one has been prosecuted over the bombings at three hotels and three churches in Colombo that killed 279 people on April 21, 2019, although a local investigation found that followers of a jihadist group were behind them.
An inquiry set up by former president Maithripala Sirisena said in a report published last month that he and his intelligence chiefs should be charged for failing to prevent the attacks.
"Our effort is to establish who was actually behind the attacks," Catholic leader Cardinal Malcolm Ranjith said in a statement on Sunday.
"This is not an issue only for Catholics. All Sri Lankans suffered after this attack."
Several Buddhist monks joined Ranjith and other protesters outside St Anthony's church, one of the sites attacked, carrying banners calling for justice.
Some banners asked "Who ran the operation behind the curtain?", and "Will the law be enforced against those who were found to be negligent?".
Ranjith told a press conference last week that he was unhappy with the lack of progress in the inquiry, and laid out an ultimatum.
"If the authorities fail to come up with answers as to who was behind the attacks by the second anniversary of the bombings, we will call for a nationwide black-flag campaign," he said.
The campaign would involve Sri Lankans flying a black flag above their homes as a sign of protest, the cardinal added.
The US Justice Department in January charged three Sri Lankans with supporting terrorism for their alleged participation in the attacks, which were claimed by the Islamic State group.
All three are in custody in Sri Lanka but have not been charged locally. The Justice Department said it would support their prosecution in the country.
At least 45 foreigners, including five Americans, were among those killed.