SAN FRANCISCO (AFP) - A judge on Friday cut US$450 million (S$557 million) from a US$1 billion award to be paid by Samsung in a landmark patent lawsuit from Apple, saying a jury had wrongly calculated the damages.

United States (US) District Judge Lucy Koh affirmed the remainder of the award, amounting to US$598.9 million, in the patent infringement case, while denying Apple's request for an increase in damages.

The decision marked the latest twist in the blockbuster trial pitting the maker of the iPhone against the surging South Korean electronics giant.

Apple had accused its rival of massive and willful copying of its designs and technology for smartphones and tablets.

But Ms Koh said the jury erred in calculating damages for some of the devices in question, including some models of the Galaxy SII smartphone and Galaxy Tab tablet, and struck down as invalid the US$450 million awarded to the Silicon Valley giant.

She ruled that a new trial would be needed to award damages for those items, as due to a "impermissible legal theory on which the jury based its award", she "cannot reasonably calculate the amount of excess while effectuating the intent of the jury".

But she encouraged both parties to have the case reviewed by an appellate court before any new trial.

The judge allowed the award to stand for 14 products, including some Galaxy smartphones and the Galaxy Tab 10.1 tablet, leaving an award of US$598.9 million.

The jury relied on Apple's calculation for lost profits dating back to 2010, when it first told Samsung of its objections, but Koh said that in most cases, the damages could only cover the period after the lawsuit was filed in April 2011.

"There are eight phones for which the jury awarded 40 percent of Samsung's profits for the entire period, but for which, during some of the damages period, infringer's profits was not an authorized remedy," the ruling read.

"The only remaining possibility is to conduct a new trial on damages for these 8 products."

The judge said Apple could have averted a new trial if it had not pursued an "aggressive" strategy by using an expert report based on a long period of infringement.

"The need for a new trial could have been avoided had Apple chosen a more circumspect strategy or provided more evidence to allow the jury or the court to determine the appropriate award for a shorter notice period," she wrote.

There was no immediate comment from Apple or Samsung.

The jury verdict last August was seen as a decisive victory for Apple, which has been seeking to boost damages and to ban some Samsung products from the United States.

Apple has been rapidly losing market share to Samsung and other manufacturers which use the free Google Android system in the smartphone and tablet computer markets.

Google's Android system was used on 70.1 per cent of smartphones shipped in the quarter, while Apple held 21 per cent of the global market, according to research firm IDC.