It's been rumbling on since March last year, and now the legal battle between Viacom and Google looks set to get even nastier.

Last spring, Viacom launched a $1bn case against Google accusing its website YouTube of massive copyright infringement.

It argued that almost 160,000 unauthorised clips of Viacom’s programming have been available on YouTube and that these clips had been viewed more than 1.5 billion times.

In July last year, as the lawyers shuffled papers, Google responded that it was working on checking technology that would make sure that copyrighted material was removed straight away.

But now, Viacom has rewritten its case and is going after the $1bn declaring that Google has done "little or nothing" to stop infringement since the case was first filed.

Viacom says: "The availability on the YouTube site of a vast library of the copyrighted works of plaintiffs and others is the cornerstone of defendants' business plan".

Earlier this month Viacom chairman Sumner Redstone told Dow Jones: "When we filed this lawsuit, we not only served our own interests, we served the interests of everyone who owns copyrights they want protected".

"We cannot tolerate any form of piracy by anyone, including YouTube ... they cannot get away with stealing our products."

Google has hit back saying that the case "threatens the way hundreds of millions of people legitimately exchange information" over the web.

Google also says that YouTube "goes far beyond its legal obligations in assisting content owners to protect their works".

And it's ready for a legal battle.

Google's vice president of content partnerships David Eun has said: "We're going all the way to the Supreme Court. We've very clear about it".