Mona Eltahawy
Mona Eltahawy tried to cover one of the controversial posters put up on New York subway by right-wing organisation FDI (Wiki Commons)

Egyptian-American writer Mona Eltahawy has been released by New York police after she was arrested for spray-painting a controversial ad on the New York subway that equated jihad with savagery.

The poster read: "In any war between the civilized man and the savage, support the civilized man. Support Israel, defeat jihad." It had been put up in 10 subway stations by right-wing American organisation Freedom Defense Initiative (FDI).

Eltahawy tried to conceal the message beneath purple spray-paint but was confronted by an FDI supporter who was patrolling the area with a camera.

A row erupted between the two and was captured on video.

Two police officers intervened and arrested Eltahawy, who was charged with criminal mischief.

"This is non-violent protest. This is what happens in America when you non-violently protest," Eltahawy can be heard saying in the video as she is led away by police.

She said she was kept in custody for 22 hours - a longer period than when she was held by Egyptian police during Arab Spring protests in Cairo, following an assault by riot police that left her with two broken arms.

"I spray-painted that racist piece of s*** poster out of principle, protected speech and non-violent disobedience. Proud & absolutely no regrets!" she tweeted after release by the NYPD.

According to the Daily Mail, FDI supporter Pamela Hall will sue Eltahawy claiming her clothing and equipment were damaged during the scuffle.

"At one point that Pam woman had her tripod at my chest," Eltahawy tweeted. "And it's all on camera via media there. I should sue her a** for assault."

The advert was originally barred by New York's transportation agency on the grounds of using demeaning language but a federal court ruled in favour of FDI.