Jackson's "wardrobe malfunction" has gone down in TV history

The US Senate has approved a bill which will see the maximum penalty for showing unsuitable material rise tenfold to $325,000 (�173,000).

A similar bill was passed by the House of Representatives in 2004, which set fines at $500,000 (�275,000).

Differences between the two bills must be worked out before the new measures can be amalgamated into one law.

"The companies who profit from using the public airwaves should face meaningful fines for broadcasting indecent material," said Republican senator Sam Brownback, who sponsored the new bill.

The Senate approved a rise in fines in June 2004, but the proposals were later dropped from the legislation.

The new bill does not change how unsuitable material is defined, or how fines should be assessed.

Record fines

Missing persons drama Without A Trace has attracted record fines

US broadcasters have been under pressure to clean up the airwaves since Janet Jackson's breast was exposed during a dance routine at the 2004 Super Bowl.

Television network CBS was fined $550,000 (�315,000) for the "wardrobe malfunction".

Currently, the maximum fine that can be imposed on an individual television station is $32,500 (�18,600) per breach.

This can multiply, however, because each network has dozens of affiliated stations around the US.

In March this year, the Federal Communications Commission proposed a record fine of $3.6m (�1.9m) for an episode of the missing persons drama Without A Trace.