(REUTERS) - BP launched its promised appeal against what it called "fictitious" and "absurd" payouts to some oil spill compensation claimants on Friday and asked a judge to temporarily halt those paid out as business economic losses.

In a filing in a federal court in New Orleans, BP said it could be "irreparably harmed" by the payouts without relief from the court, because they could cost it billions more than it had budgeted for when it agreed to a settlement in April 2012.

BP was appealing a March 5 ruling that upheld the way the compensation is being paid to business claimants wanting recompense for losses caused by the 2010 spill, which killed 11 men and spewed 4 million barrels of oil into the sea. The ruling overrode objections from BP, which has been finding the payments much more generous than it had accounted for.

The ruling, by the same court where BP and other companies have been on trial for separate civil charges stemming from the spill since February, has reopened a part of the saga that appeared to have been settled almost a year ago.

The settlement covers a class action claim for economic, property and medical compensation from more than 100,000 individuals and businesses.

At the time of the settlement, BP estimated the bill would be US$7.8 billion (S$9.5 billion) - already making it one of the biggest settlements of its kind in United States (US) history. The actual amount is uncapped and dependent on decisions made by Mr Patrick Juneau, a lawyer from Louisiana who administers the payments under a complex set of rules set out by the agreement.

As the payments started to flow out, BP realised that the funds it had set aside would not be enough. At first it added more, reaching US$8.5 billion by the end of 2012, while complaining that the payments to businesses were too generous and the terms of the settlement were being misinterpreted.

On March 5, US District Judge Carl Barbier, who is presiding over the trial, upheld Mr Juneau's methods.

Two days later BP said it would appeal, and it actually reduced the sum earmarked for payments back down to US$7.7 billion to underline its disapproval.