A helicopter crash in Egypt's Sinai Peninsula involving a multi-national observer force killed eight people on Thursday -- six Americans, a French national and a Czech citizen, the force said.

"During a routine mission in the vicinity of Sharm el-Sheikh, Egypt, nine members of the Multinational Force and Observers (MFO) were involved in a helicopter crash," it said in a statement posted on its website.

"We are deeply saddened to report that eight uniformed MFO members were killed; six US citizens, one French, and one Czech," it added.

Another member of the force, an American, survived and was medically evacuated, the MFO added.

The Israeli army said separately that it had offered to provide immediate medical assistance.

An army "helicopter carrying elite search and rescue soldiers... was scrambled to the Ramon airport (in southern Israel)," its spokesman Jonathan Conricus said.

The peacekeeping force was set up by Israel and Egypt to supervise parts of their 1979 historic peace treaty after the UN did not did not approve a peacekeeping force for the Sinai.

The force was established as an alternative to the UN mission, but has consistently had significant international backing, notably from the United States.

Egypt's Sinai Peninsula is facing a hardened insurgency affiliated with the Islamic State group in the north of the restive region while the south boasts touristic resort towns by the Red Sea, near where the crash happened.

In February 2018, security forces launched a nationwide operation against militants, focused on North Sinai.

More than 930 suspected militants have been killed in the region along with dozens of security personnel, according to official figures.

The multi-national force said in its statement that it would conduct an investigation to determine the cause of the accident.

"At this point, there is no information to indicate the crash was anything except an accident," the MFO said.

The MFO currently has more than 1,100 troops from Australia, the United States, Canada and France. The force's website lists only one French member in its contingent, a liaison officer.