iPhone chip supplier Qualcomm faces a new set of antitrust allegations from a group of four companies that assemble the iPhone and other products on behalf of Apple.

Hon Hai Precision Industry Co., Wistron Corp, Compal Electronics Inc and Pegatron alleged that Qualcomm violated two sections of the Sherman Act, a U.S. antitrust law.

The accusations, made in a filing late Tuesday in U.S. District Court for the Southern District of California, are counterclaims to a Qualcomm lawsuit filed in May seeking to force the contractors to pay Qualcomm license fees that Apple directed them to stop paying. If successful, the counter-claims could cost Qualcomm billions of dollars in refunded fees and damages, Apple said.

"Qualcomm has confirmed publicly that this lawsuit against our clients is intended to make a point about Apple and punish our clients for working with Apple," Theodore J. Boutrous, a lawyer for the four companies, said in a statement. "The companies are bringing their own claims and defenses against Qualcomm."

Qualcomm supplies Apple with modem chip technology that lets iPhones connect to cellular data networks. The two companies have been fighting over the nature of Qualcomm's business model of linking the sale of chips and patent licenses.

In January, Apple sued Qualcomm alleging that the company had withheld nearly $1 billion of patent license rebates it owed Apple in retaliation for Apple's cooperation with South Korean regulators. Apple told its contract manufacturers to withhold license payments from Qualcomm while the dispute played out, which prompted Qualcomm to sue them in May.

Also Wednesday, Qualcomm said it had filed two new patent-infringement suits against Apple, this time in Germany. The patents, for ways to transmit information without draining battery life, are the European counterparts to those that are part of a case Qualcomm filed with a trade agency in Washington seeking to halt imports of Apple products into the U.S. market.