Sri Lanka's High Court has convicted 15 men who had been charged with plotting the 2019 Easter Sunday bomb attacks that killed 270 people and injured more than 500, the BBC reports.

Nine other men were acquitted.

Those found guilty include Naufer Moulavi, who prosecutors said masterminded the suicide bombings.

All the bombers who carried out the attacks died in the blasts.

The coordinated blasts at three churches and three luxury hotels were the deadliest in Sri Lanka since the end of its civil war in 2009. Forty-five foreigners were among the dead.

Investigators have previously blamed the bombings on Islamist extremists, and the 25 men indicted were from Sri Lanka's Muslim minority. One died in custody.

The accused had been charged with more than 23,000 offenses, including murder, conspiracy to commit terrorism and possessing firearms.

More than 2,300 people gave evidence for the prosecution.

There were also 2,076 pieces of evidence, including explosives, swords and firearms.

Last month, two former senior officials were sentenced to death for criminal negligence that led to the bombings.

Death sentences are usually commuted to life in prison in Sri Lanka due to a decades-old moratorium on executions.

For years, Sri Lankans have held regular demonstrations demanding justice for the victims of the Easter attacks.