Sri Lanka's police stepped up the already tight security in the capital on Monday ahead of a mass protest over the assassination of a moderate Tamil MP, officials said.
Several roads in the city were closed and the checking of vehicles intensified as anti-war demonstrators prepared to stage a march in Colombo denouncing Friday's slaying of human rights campaigner Nadarajah Raviraj.
"We are asking motorists to avoid the route taken by the demonstrators," a police spokesman said.
"We have tightened security in the city today as a precautionary measure."
Raviraj's Tamil National Alliance and the authorities clashed Sunday over funeral arrangements.
The TNA said a request for the funeral cortege to travel to the northern peninsula of Jaffna by road was turned down by the government.
Raviraj, 44, was shot dead by unidentified gunmen in Colombo Friday morning. He represented the Jaffna district, 400 kilometres north of Colombo.
Defence officials confirmed the request was rejected, but said they had offered air transport to Jaffna.
A large group of political parties and anti-war activists have declared Monday a day of protest and said the broad-daylight assassination demonstrated the level of lawlessness in the island.
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.
The TNA party was a proxy of the Tigers, but Raviraj was regarded as a moderate who had never taken up arms.
He spoke Sinhalese and was a personal friend of President Mahinda Rajapaksa, who has asked the foreign ministry to invite British police to help probe the killing.
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.