Qualcomm Inc. has launched a global antitrust campaign against Arm Holdings Plc as the two longtime business partners jockey for advantage in the computing semiconductor market.

In private meetings and confidential filings to regulators on three continents, Qualcomm is arguing that Arm — its biggest supplier — is guilty of anticompetitive behavior, according to people familiar with the matter.

Qualcomm’s complaints to the European Commission, US Federal Trade Commission and Korea Fair Trade Commission allege that Arm is hurting competition by restricting access to its technology after operating an open network for more than 20 years, said the people.

Qualcomm, the No. 1 maker of chips that run phones, contends that Arm created a heavy reliance on its technology through an open licensing model, which also fostered a thriving chip industry. Qualcomm is telling competition authorities around the world that that dynamic market is now threatened as Arm restricts access to boost profits through its own chipmaking ambitions, said the people, who asked not to be named discussing confidential matters.

A spokesperson for Qualcomm declined to comment. Spokespeople for the EU, the FTC and the KFTC declined to comment.

Arm says it’s confident it will prevail. “Arm remains focused on enhancing innovation, promoting competition, and respecting contractual rights and obligations,” the company said in an emailed statement. “Any allegation of anticompetitive conduct is nothing more than a desperate attempt by Qualcomm to detract from the merits and expand the parties’ ongoing commercial dispute for its own competitive benefit.”

Both companies are trying to position themselves to benefit from a boom in computing demand — for everything from desktops to AI systems — as the market for smartphone chips, which had fueled much of their growth in recent years, has become more sluggish.

Qualcomm’s complaints to global regulators track with arguments the San Diego-based company has made in a recent court case Arm brought in Delaware. In that fight, Qualcomm successfully argued that it didn’t need a new license to use Arm’s technology for a chip startup it had acquired.

Qualcomm laid out its global beef in its Delaware countersuit, saying that following Arm’s acquisition by Japan’s SoftBank Group Corp. and the failure of an attempted sale to Nvidia Corp., “Arm is now grasping for any means — fair or foul — of padding its bottom line and stock price.”

Arm has said it plans to seek a retrial. In late January, the two companies said they plan to hold court-ordered mediation talks required by the Delaware judge before a decision on whether a retrial will be allowed. If a deal isn’t reached, the conflict could take years to resolve, distracting both companies from their core businesses.

The antitrust and courtroom fights show two longtime business partners pitted against each other, sparring for legal victories to create leverage over licensing agreements that cover hundreds of millions of processors that go into mobile phones and generate billions of dollars of profits each year.

In late December, before its court win, Qualcomm lodged a competition complaint against Arm in Europe accusing it of trying to restrict access to its licenses and withold key technology as it sought to compete more directly with Qualcomm, according to some of the people familiar.

Arm has received the EU complaint and is in the process of responding, some of the people said.

Qualcomm met earlier this year with FTC officials in Washington about its concerns, some of the people said. Among its complaints, Qualcomm has accused Arm of withholding critical technology it should provide under its license agreements, two of the people said. Qualcomm has also raised its concerns with South Korea’s antitrust regulator, some of the people said.

Arm, which is based in the UK and majority-owned by SoftBank, doesn’t make its own chips. Rather it sells chip designs and licenses a so-called instruction set — code used by software to communicate with processors. Both chipmakers like Qualcomm and device makers like Apple Inc. rely on Arm licenses for their products.

Under Chief Executive Officer Rene Haas, Arm has shifted from providing foundational technology to chipmakers to building more complete designs, making it more of a competitor with its traditional customer base, including Qualcomm.

To be sure, Qualcomm has faced scrutiny itself from regulators around the world, but has emerged largely victorious. Qualcomm won a wide-ranging fight with the EU and also prevailed on appeal against the FTC, which had alleged that the company was using predatory licensing activities.