Sri Lanka's police stepped up already tight security in the capital on Monday ahead of a mass protest over the assassination of a moderate Tamil legislator and growing rights abuses, officials said.
Several major roads in the city were closed and vehicle inspections intensified as anti-war demonstrators prepared to stage a march in Colombo denouncing Friday's slaying of human rights campaigner Nadarajah Raviraj.
His Tamil National Alliance (TNA) party accused the government of trying to sabotage the demonstration by blocking buses transporting mourners and sympathisers to the capital.
"They are preventing people attending the rally," legislator Suresh Premachandran said. "We have information that buses were turned away at Puttalam (in the north-west)."
Local authorities turned down a request to allow the remains of Raviraj to be brought to the main Colombo Town Hall building and the demonstration would now be held in an adjoining open park, Premachandran said.
In the main business centres of Pettah and Fort in Colombo, shops owned by minority Tamils remained shut as a sign of mourning and protest, while many put up white flags.
A group of anti-war activists asked workers to take part in the demonstrations and pressed authorities to bring Raviraj's killers to justice and put an end to human rights abuses committed by security forces and paramilitaries.
Raviraj, 44, was shot dead by unidentified gunmen in Colombo Friday morning. He represented the Jaffna district, 400 kilometres (250 miles) north of Colombo.
The main opposition United National Party (UNP) said the government must accept responsibility for the killing -- the second of a TNA member of parliament in a year -- and ensure the killers were brought to justice.
Tamil Tiger rebels on Saturday conferred their highest civilian honour on Raviraj.
Raviraj's TNA and authorities clashed Sunday over funeral arrangements. The funeral is scheduled to be held Wednesday afternoon in the Jaffna district.
The TNA said a request for the funeral cortege to travel to the northern peninsula of Jaffna by road was rejected by the government.
Defence officials confirmed the request was rejected, but said they had offered air transport to Jaffna.
The TNA party is a proxy of the Liberation Tigers of Tamil Elaam, but Raviraj was regarded as a moderate who had never taken up arms.
He spoke Sinhalese and was a personal friend of President Mahinda Rajapakse, who has asked the foreign ministry to invite British police to help investigate the murder.
The death was a serious breach of security in Colombo, where police and the armed forces have maintained a high state of alert for several weeks.
The killing came amid an upsurge in fighting in the island's separatist conflict. Some 3,300 lives have been lost in the past year, despite a 2002 truce.