Mobs torched Muslim-owned businesses in a central Sri Lanka district on Wednesday as hundreds of police and troops struggled to restore order after days of rioting.
The soldiers poured into Kandy to reinforce police but arson attacks persisted even though the government has imposed a nationwide state of emergency and suspended the internet locally to quell attacks by mobs from the majority Sinhalese community.
Prime Minister Ranil Wickremesinghe said several arson attacks were reported from Kandy on Wednesday, and internet access curbed to prevent the spread of hate speech.
"We have temporarily blocked several social media websites to prevent them from being used to instigate violence," Wickremesinghe said in a statement.
He said a "hand bomb" carried by a member of a mob had exploded at the Kandy suburb of Ambatenna, but did not give further details. Police said there had been several casualties.
President Maithripala Sirisena on Wednesday toured Kandy, where rioters defied curfews and clashed with police who used tear gas to disperse them.
"I have ordered that the full force of the law be used against trouble makers," Sirisena said.
Schools were shut across Kandy, a hill resort famed for its tea plantations and Buddhist relics.
A curfew was extended until Thursday evening in the troubled district popular with tourists, officials said.
Telecommunication providers were instructed to block Facebook nationwide and suspend internet services in the area after police warned that rioters were using social media to urge violence against Muslims.
At least three police officers were wounded overnight at Menikhinna in the district of Kandy, which has been a focus of the new trouble, said police spokesman Ruwan Gunasekera.
Foreign governments issued travel warnings after Sri Lankan authorities granted sweeping powers to police and troops to arrest and detain suspects.
"The state of emergency may include curfews in specific locations," the UK government said on its website.
"You should exercise caution, avoid protests and rallies and comply with local security requirements."
The US State Department said further violence was possible and advised visitors to monitor local media for updates.
The United Nations condemned the violence and urged Colombo "to ensure that appropriate measures are swiftly taken to restore normalcy in affected areas".
More than 150 homes, shops and vehicles belonging to Muslims were set ablaze by mobs of Sinhalese rioters on Monday and Tuesday.
The violence began after a man from the mainly Buddhist Sinhalese majority died at the hands of a Muslim mob last week.
The trouble escalated when a Muslim man was found dead in a burned building on Tuesday.
There was no immediate estimate of the damage from Wednesday's arson attacks.
Parliament on Tuesday issued an apology to the Muslim minority for the violence.
City planning minister Rauff Hakeem described the riots as a "monumental security lapse" and recommended disciplinary action against those responsible.