Updated

Traffic jerked to a standstill as rubbernecking motorists ogled a pornographic clip posted by hackers on big-screen video billboards in Moscow, Russian news agencies reported Friday.

The company that operates the billboards, Panno.ru, said hackers were behind a graphic sex video broadcast late Thursday night on two roadside screens along Moscow's Garden Ring Road, one of the city's busiest arteries.

"This was an attack by hackers on the computers, as a result of which one of the commercial video clips was swapped for an indecent video," Panno.ru commercial director Viktor Laptev told RIA-Novosti.

He speculated the attack could have been linked to competition on the advertising market, or simply "hooliganism."

Witnesses said traffic crawled to a halt as unbelieving motorists craned their necks to stare at the X-rated clip, which ran for about 20 minutes on the oversized screens.

"Within three minutes we found it out, and within fifteen minutes the screen was shut off," the deputy head of the Moscow city advertising committee, Alexander Menchuk, was quoted as saying by Interfax.