CAIRO, July 10 (Reuters) - Two people were killed and six wounded when Islamist militants attacked an Egyptian security forces checkpoint late on Tuesday using rocket-propelled grenades and heavy machine guns in the lawless North Sinai province, security sources said.

It was not clear whether the casualties were civilians or security personnel in the attack in the remote village of Sadr El-Heytan, located in the centre of the province.

The attack came shortly after another assault in the town of Rafah, when security forces and militants exchanged gunfire. Another police checkpoint was also attacked nearby, the sources added.

Hardline Islamist groups based in North Sinai have exploited the collapse of state authority after the 2011 uprising that toppled autocratic leader Hosni Mubarak to launch attacks across the border into Israel and on Egyptian security targets.

The violence has risen since last week's overthrow of elected Islamist President Mohamed Mursi by the military.

Last Sunday, one Egyptian soldier was killed and a police officer was wounded in an attack on a security checkpoint in Sinai, and five security officers were killed in skirmishes with suspected militants on Friday.

The Salafi Jihadi group, one of the biggest Sinai-based Islamist militant groups, had said in a statement that "current events ravaging the country" were affecting Sinai and threatened to launch attacks on police and military forces in Sinai. (Reporting by Yusri Mohamed in Ismailia and Ali Abdelaty in Cairo, writing by Yasmine Saleh; editing by Mike Collett-white)