He was killed by a roadside bomb alleged to have been planted by the Sri Lanka Army's Long Range Reconnaissance Patrol (Deep Penetration Unit).
[5] On 6 March 2008 Sivanesan was travelling north along the A9 highway to his home in Mallavi after attending Parliament in Colombo.
He crossed the frontline checkpoint at Omanthai, Vavuniya District and entered the territory controlled by the Liberation Tigers of Tamil Eelam.
Thirty minutes later, at around 1:20pm, when Sivanesan's vehicle was near Maankulam, Mullaitivu District, some 35 kilometres (22 mi) north of the Omanthai checkpoint, four claymore mines exploded in a row.
The Tamil National Alliance immediately blamed the Sri Lankan government security forces for the assassination.