* Competition watchdog seeks ruling on "anti-competitive purpose"
* Watchdog alleges Pfizer sought to deter Lipitor rivals
* Company declines to comment on watchdog's appeal (Adds "no comment" from Pfizer)
MELBOURNE, June 25 (Reuters) - Australia's competition watchdog said on Monday it would appeal to the nation's high court for a ruling on whether Pfizer Inc used its market power to limit competition for its cholesterol-lowering drug Lipitor.
The Australian Competition and Consumer Commission (ACCC) lost an appeal in May in a case alleging that Pfizer had abused its market power by offering big discounts and rebates on Lipitor to pharmacies, which bought large quantities of the drug and agreed to limit re-supply of competing generic atorvastatin products.
The commission said while the full Federal Court last month found that Pfizer had taken advantage of its market power, the court rejected the commission's view that Pfizer had done so in order to lessen competition.
So the ACCC has decided to appeal to the High Court of Australia.
Pfizer declined to comment on the commission's decision to appeal to the High Court.
"The ACCC is seeking clarity from the High Court on how to assess anti-competitive purpose, an important issue raised by this case," ACCC Commissioner Sarah Court said in statement.
The drug Lipitor generated annual sales of more than A$700 million ($520 million) for Pfizer in Australia before the company's patent expired there in May 2012, the commission said, when it launched the case against Pfizer in 2014.
$1 = 1.3481 Australian dollars Reporting by Sonali Paul, Editing by Sherry Jacob-Phillips