"The aim of the LTTE (Liberation Tigers of Tamil Eelam) is to have a backlash against the Tamils and to undermine our efforts to find a peaceful solution," President Mahinda Rajapakse said in a statement released by his office Sunday.

He appealed to the Sinhalese community to show maximum restraint to two separate bomb blasts blamed on suspected Tamil rebels on buses travelling the main southern coastal highway from the capital Colombo at the weekend.

An LTTE defence spokesman, Rasiah Ilanthirayan, denied any responsibility for the blasts, which occurred on a road widely used by tourists to reach southern beaches along Sri Lanka's west coast.

Officials said 11 people were killed and 47 wounded Saturday when a suspected female suicide bomber blew up a bus near Ambalangoda, 85 kilometres (53 miles) south of Colombo. The attack followed a bus blast late Friday when six passengers were killed and another 70 wounded near Colombo.

Authorities blamed both attacks on the LTTE, which is fighting for an independent Tamil homeland in a conflict that has claimed more than 60,000 lives since 1972.

Fighting has escalated in the past year, with more than 3,800 people dead despite a nominal ceasefire agreement reached in 2002.