A new law in New York means that all video games sold in the state must clearly label ratings for violent content.

The law, which was signed this week by Gov. David Paterson, has been slammed by rights groups who say it is unconstitutional.

The New York Civil Liberties Union (NYCLU) has said that it planned to mount a legal challenge against the law as it raised free speech concerns.

The group has said that similar laws in other states such as California, Illinois, Michigan, Minnesota and Washington state have been thrown out for that reason.

In the U.S, the video gaming industry voluntarily submits to ratings, on a system very similar to that used by movies.

However, the new law states that it is compulsory for games that are already rated to be labelled, and also requires new video game consoles to be installed with parent-controlled lockout features by 2010.

"This legislation will provide information and educate consumers to help them make better choices for their children," said state Sen. Andrew Lanza, a bill sponsor.

However, NYCLU's legislative director Robert Perry said the new law was a "back-door" way of regulating video game content.

The law also establishes an advisory council to study "the connection between interactive media and real-life violence in minors exposed to such media" and to evaluate the ratings issued by the Entertainment Software Ratings Board.