European Commission (EC) competition regulators have dropped a long running anti-trust investigation into Qualcomm.

A number of companies complained in November 2007 that Qualcomm had broken previously established agreements to keep mobile phone component patent royalty fees at an acceptable level, but had since withdrawn their claims.

The firms in question were Broadcom, NEC, Nokia, LM Ericsson, Panasonic Mobile Communications and Texas Instruments.

The EC regulators said at the time that the investigation "will focus on whether Qualcomm is dominant and whether the licensing terms and royalties imposed by Qualcomm are, as alleged by the complainants, not fair, reasonable and non-discriminatory".

However, in a statement issued today, regulators said it is to close formal proceedings.

"All complainants have now withdrawn or indicated their intention to withdraw their complaints, and the Commission has therefore to decide where best to focus its resources and priorities," the statement read.

"In view of this, the Commission does not consider it appropriate to invest further resources in this case."

Ericsson said in a statement today that it had withdrawn its complaint, but that it would continue to work with regulators "in relation to Qualcomm's licensing practices".

"Ericsson has co-operated with the EC's four-year investigation to ensure that consumers in Europe do not pay higher prices because of Qualcomm's unfair licensing practices," said Nina Macpherson, vice president and head of Ericsson's general counsel's office.

"Our goal remains the same: to prevent any patent owner from distorting competition and extorting unreasonable, excessive royalties that reflect neither patent value nor R&D investments in the standards concerned."

Ericsson had already won a case against Qualcomm in Korea resulting in the largest fine ever imposed by the Korean Fair Trade Commission, and in Japan where Qualcomm has been ordered to "cease and desist" certain licensing practices.