European Union antitrust regulators may open an investigation into Qualcomm, the world's No. 1 mobile chipmaker, based on a four-year-old complaint by a unit of rival Nvidia Corp, three people familiar with the matter said on Tuesday.

British cellphone chipmaker Icera, acquired by Nvidia in 2011, took its grievances to the European Commission in June 2010, accusing Qualcomm of anti-competitive behavior.

"The Commission may open a case after the summer," said one of the sources, who declined to be named because of the sensitivity of the matter.

A possible EU probe comes as Qualcomm seeks to end an investigation by China's pricing regulator into monopoly practices.

The EU competition authority in 2010 scrapped a four-year probe into Qualcomm after Swedish mobile telecom gear maker Ericsson and U.S. rival Texas Instruments withdrew their objections against the company.