Qualcomm has said that Apple is $7 billion behind on royalty payments to the chip maker, as heard in a San Diego federal court hearing.

As reported by Reuters, the latest development in the ongoing legal battles between the two US companies has seen Qualcomm accused of unfair licensing practices, and Apple accused of patent infringement.

Apple said that Qualcomm is forcing it to pay for the same patents twice, the report says – once when Apple uses Qualcomm’s chip in iPhones and then again through patent royalties. Qualcomm, meanwhile, said Apple had agreed to its business model for year and is “seeking to destroy it”, the report says.

In an amendment by Qualcomm to court filings earlier this month Qualcomm alleged: “Apple has engaged in a years-long campaign of false promises, stealth and subterfuge designed to steal Qualcomm’s confidential information and trade secrets for the purpose of improving the performance and accelerating time to market of lower quality modem chip sets, including those developed by Intel Corp.”

Needless to say, Apple denies those allegations.

Read more: Is Apple about to turn chip maker?

Qualcomm has for years supplied parts for Apple’s iPhones — including last year’s iPhone X, 8, and 8 Plus models. But earlier reports quoted Qualcomm as saying that Apple will exclusively use Intel modems in its phones.

TechInsights reported that this year’s iPhones carry chips made by Intel and Toshiba.

Apple paid £455 million ($600 million) to UK-based Dialog Semiconductor earlier this month as an attempt to strengthen its position in chips in Europe

Qualcomm Chips Drive Ongoing Back and Forth

Qualcomm and Apple’s legal battle goes back to January 2017, when Apple brought forward a $1 billion case relating to withheld payments.

Qualcomm then sued Apple for alleged iPhone patent infringement that July, with Cupertino allegedly infringing on six patents in Qualcomm chips.

Last November, Apple accused Qualcomm’s Snapdrogon mobile chips that power Android devices as infringing on its patents.

Qualcomm then fired back with more patent infringements complaints later that month.

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