The European Union's highest court has upheld a €52.5 million ($69 million) antitrust fine levied against AstraZeneca for blocking the entry of cheaper rivals to its then bestseller ulcer drug Losec.

"The abuses must be characterised as serious infringements, and consequently the amount of the fine cannot be reduced for those reasons," the Luxembourg-based EU Court of Justice (ECJ) said on Thursday.

The General Court, Europe's second-highest, had backed the European Commission in 2010 against British drugmaker AstraZeneca, but cut the penalty to €52.5 million from an original 60 million.

The Commission, which acts as EU antitrust and competition authority, originally penalised AstraZeneca for actions that regulators said had kept Losec prices artificially high.

Officials at AstraZeneca were not available to comment.

Regulators on both sides of the Atlantic have generally frowned on actions by brand-name companies to delay either the production or sale of cheaper medicines to protect their own products.

The ECJ decision was an endorsement of the European Commission's policy of getting tough on tactics used by drugmakers to block cheap generics - a growing issue for the industry as many medicines reach the end of their patent life.

A finding in favour of AstraZeneca would have been a significant setback for EU antitrust regulators who have invested considerable time and money in a high-profile battle against pharmaceutical industry abuse in this area.

The case against AstraZeneca hinged on charges by the Commission that the company gave misleading information related to Losec to several national patent agencies from 1993-2000.

This blocked or delayed the entry of cheaper generics to the market and also prevented parallel imports of the drug - when the same patented drug is brought in more cheaply from another EU country.

The AstraZeneca case prompted EU antitrust enforcers to start an inquiry into the pharmaceutical sector in early 2008, which resulted in a critical report on methods used by the industry to delay generic competition and subsequent raids on drugmakers.