Samsung Electronics and Intel are backing the U.S. Federal Trade Commission's lawsuit accusing Qualcomm of trying to corner the market for semiconductors used in smartphones.

The South Korean company, one of Qualcomm's largest customers, and Intel, one of its biggest competitors, filed arguments Friday in support of the FTC's case against Qualcomm. Both contend the San Diego-based company stops them from competing fairly against it by leveraging patents that cover the fundamentals of modern phone systems.

"Because the FTC's attempt to shed light on Qualcomm's anticompetitive practices is of great importance to the industry as a whole, several other companies and trade associations also have filed briefs supporting the FTC. Intel's brief, in particular, illuminates the adverse impact that Qualcomm's conduct is having on competition and innovation, and explains how that conduct violates the antitrust laws in several different ways," said Intel.

Intel's Amicus Brief is available here.

Samsung claims its in-house chip unit is artificially held back by Qualcomm's unwillingness to license its technology.

"Despite having requested a license from Qualcomm, Samsung cannot sell licensed Exynos chipsets to non-Samsung entities because Qualcomm has refused to license Samsung to make and sell licensed chipsets," Samsung said in a filing.

Qualcomm is trying to fend off a series of legal and regulatory challenges to its business practices around the world, including a suit by Apple, one of its largest customers. The chipmaker gets most of its profits from selling the rights to use patents that are essential to all mobile phone systems featuring high-speed connectivity.

Earlier Friday, the FTC urged a judge to reject Qualcomm's request for dismissal of the agency's case.