A Moscow court has jailed a Russian hacker for 18 months after he altered an electronic advertising billboard so that it screened a pornographic video, the RIA Novosti news agency reported.

Hacker Igor Blinnikov stopped traffic in January last year by breaking into a computer system and screening a graphic sex video for around 10 minutes on a video billboard beside a busy highway in central Moscow in the late evening.

Blinnikov, who comes from the southern Russian city of Novorossiisk, was found guilty of illegally gaining access to information on a computer and distributing pornographic materials.

He called the video prank on Moscow's Garden Ring highway a "joke that went wrong" and said that he would appeal against the sentence.

He had earlier been convicted of attempting to deal in marijuana and was handed a sentence of six years by Moscow's Zamoskvoretsky court, a year of which he has already served in detention.