Rebel infighting kills at least 5 in Syrian town near border with Iraq

Activists say heavy clashes between Syrian opposition fighters and Islamic extremist rebel factions near the Iraqi border have killed at least five people.

The Britain-based Syrian Observatory for Human Rights monitoring group says the ongoing battles Saturday in the town of Boukamal pit the al-Qaida-affiliated Islamic State of Iraq against more moderate rebel brigades.

Infighting among rebel groups, particularly between al-Qaida-linked extremist factions and more moderate units, has escalated in recent months. The violence undermines the opposition's primary goal of overthrowing President Bashar Assad.

It also complicates efforts by the U.S. and its allies to provide greater support to the Syrian opposition.