Updated

Syria's main opposition bloc said Wednesday it will fight on to topple President Bashar al-Assad, and that any political solution to the conflict must lead to the fall of the regime.

The National Coalition's statement comes after G8 leaders said they were "committed to achieving a political solution" to the Syrian conflict.

The Coalition also called on the United Nations to investigate the alleged use of chemical weapons by Assad's forces in rebel-held areas.

"The Syrian National Coalition is committed to any political solution that puts an end to the bloodshed, and achieves the Syrian people's aspirations to bring down the Assad regime," it said in a statement.

The group added it "reserves the right to use all means at its disposal" to bring Assad down, "chiefly military action".

"The Assad regime has continuously killed civilians using ballistic missiles, chemical weapons and warplanes. It is the only source of terrorism in Syria.

"In order to achieve a lasting peace in Syria, efforts by all countries should be focused on fighting the regime alone."

The opposition bloc meanwhile called on the UN to investigate the alleged use of chemical weapons in Syria.

"The Coalition renews its invitation to the UN commission of enquiry to visit Syrian liberated (rebel-held) areas, in order to investigate... and confirm the Assad regime's use of chemical weapons against the Syrian people," it said.

The United States, Britain and France have accused the Assad regime of using banned arms, including the nerve gas sarin, in attacks that have killed scores of people.

Damascus has repeatedly denied such accusations.