Authorities in Iran may find the latest social media campaign for women's rights difficult to cover up.

Under Islamic law in force in Iran since the 1979 revolution, women must wear a loose veil, known as hijab, that covers the head and neck while concealing their hair.

But internet-savvy men in Iran and around the globe are donning the veils of their wives, friends and girlfriends in pictures posted to Facebook and Twitter to protest the Islamic Republic's strict religious laws.