Unidentified men hurled grenades at a Tamil newspaper office in the capital of Colombo, killing one person and injuring two others.
Two grenades were hurled at a branch office of the Sudar Oli newspaper, which has alleged links to the country's Tamil Tiger rebels, a police officer said.
The attack came eight days after two bombs were thrown at another branch of the newspaper in Colombo. No one was injured since the bombs did not explode.
The victim in Monday's attack was a security guard, said K. Rathnasingham, editor of the newspaper. Two others, including a proofreader, were injured in the evening rush-hour explosion and taken to the hospital.
"This is the time that most of our staff leave office," he said.
Staff members said the attackers had arrived on a bicycle and that the explosions occurred seconds apart.
Ratnasingham said at least four vehicles were damaged.
He declined to say who may have been behind the assault but said it was the third attack by those trying to silence the newspaper.
"Even if just one person remains we will continue the newspaper," he said, "They will not silence us."
Sri Lanka's bomb disposal squad had cordoned off the area and police, soldiers and commandos had stepped up security.
Last week, a Sudar Oli cameraman was assaulted and arrested while covering a Marxist party protest in the capital. The protesters accused him of being a Tamil rebel. He was handed over to the police and later released.
The Marxists denied that their supporters were responsible for the attack.
The newspaper is one of the most popular among minority ethnic Tamils in the city and the northern region.
Several journalists have been killed in Sri Lanka in the past few years, but no one has been convicted in any of the murders.
Attacks on ethnic Tamil journalists have increased since a split last year within the Tamil Tiger rebel group. The breakaway faction accuses most news organizations of favoring the mainstream faction.
On Aug. 12, Relangi Selvaraja, a popular Tamil broadcaster, was fatally shot along with her husband at a shop they ran in Colombo. They reportedly were supporters of a Tamil political party that opposes the rebels.
In May 2004, Iyathurai G. Nadesan, who worked for the independent Virakesari Tamil newspaper, was fatally shot in the eastern town of Batticaloa as he rode on a motorbike to his office.
This year, Dharmeratnam Sivaram, who ran the pro-rebel TamiNet Web site, was abducted on April 28, and his body was found the following day in the capital, Colombo.
The Tamil Tigers began fighting in 1983 for a separate homeland for minority ethnic Tamils in the country's north and east, claiming discrimination by the majority Sinhalese. The conflict killed nearly 65,000 people before a cease-fire signed in February 2002.
Post-truce peace talks have been stalled since 2003 over rebel demands for wide autonomy, the AP reports.