For the first time, a company has been reprimanded by the Advertising Standards Authority (ASA) for a piece of 'viral advertising'.

These ads depend on being interesting enough for people who view them to forward to friends.

The advertisement, which consisted of a short video clip, was for the game Mortal Kombat: Shaolin Monks.

Both of the websites on which it was placed are aimed at mature audiences and businesses, and the ad was marked as suitable only for adults.

However a scene whiere two office workers are forced to fight, stabbing each other and ending in a violent death, generated a complaint.

The ASA agreed with the complainant and said that although the advertisement was intended to be humourous, it was irresponsible because it both condoned and glorified violence.

The ASA has told Midway Games, the maker of the game, not to repeat the approach, and to consult the Committee of Advertising Practice (CAP) before producing ads in future.

At the moment, the rules are unclear on what online material the ASA has jurisdiction over. The CAP, which sets the rules, is expected to announce in the next three months that the ASA will have control over viral advertising on the internet.

Anyone concerned about a piece of advertising on the internet or elsewhere can make a complaint to the ASA.

A spokeswoman for the ASA said: "Where it is an ad and people are actively encouraged to download and forward it, that's viral marketing and that falls within our remit."