Anglo-Swedish drugs giant Astra Zeneca were among the drugmakers that were raided by EU antitrust officials this week, the company confirmed Friday.

The forced entry was part of a probe into whether drugmakers colluded to keep cheaper copies of medicines off the market, Bloomberg News said.

“This shows that the commission is serious in pursuing the issues it raised in its pharma-sector investigation,” Lesley Ainsworth, a partner in London with law firm Hogan Lovells, told the news bureau.

The Anglo-Swedish company said in October its third-quarter net profits tumbled on the back of competition from generic drugmakers. "As expected, the impact of generic competition on several products and the absence of pandemic flu vaccine revenue led to a challenging quarter in the US.", the firm said in its report.

Astra Zeneca said that a number of its sites in Europe had been visited this week in connection with a European Commission probe into "pay for delay" generic drug deals between pharmaceuticals companies. The raids were focused on its top-seller heartburn drug, Nexium.

“The commission has reason to believe that the companies concerned may have acted individually or jointly, notably to delay generic entry for a particular medicine,” the EU executive, which declined to name the companies, said in an e- mailed statement. “This could be a potential violation of EU antitrust rules.”