CAIRO - Egypt's police and military killed 12 Egyptians and Mexicans and injured 10 when they accidentally shot at a Mexican tourist convoy whilst engaging militants in the country's western desert, the ministry of interior said on Monday.

"The incident resulted in the death of 12 Mexicans and Egyptians and the injury of 10 others who have been transferred to hospitals," the ministry said in a statement.

It added that the convoy was made up of four four-wheel drive vehicles and that there would be an investigation into how and why the tourists entered an off-limits area.

Egypt is battling an insurgency that gained pace after the military ousted Islamist President Mohamed Mursi of the Muslim Brotherhood in mid-2013 after mass protests against his rule.

The insurgency, mounted by Islamic State's Egyptian affiliate, has killed hundreds of soldiers and police and has started to attack Western targets.