The Cupertino, Calif.-based company has sued Qualcomm in a U.K. court, accusing the chipmaker of violating patents and design concepts Apple owns. Details on exactly which patents Qualcomm has violated and why Apple (AAPL) believes Qualcomm has violated the patents were not disclosed in the public court records, according to Bloomberg, which earlier reported on the lawsuit.

The lawsuit is the latest in a string of disputes Apple and Qualcomm (QCOM) have engaged in around the world.

The main dispute resides in the U.S., where Apple has accused Qualcomm of using its position as a prominent chipmaker to hurt competition in the mobile marketplace. Apple, which has used Qualcomm chips for its iPhone’s wireless connectivity, claims Qualcomm owes the company $1 billion in rebates the chip maker allegedly held back after Apple spoke to South Korean regulators about Qualcomm’s business practices.

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According to Apple, Qualcomm has violated competition laws by insisting on charging its customers expensive royalties when they don’t use Qualcomm chips in their devices. In January, analysts said that Apple pays approximately $15 to Qualcomm in royalties for using the company’s patented wireless technology. However, if Apple or others don’t use Qualcomm chips but those processors might still rely upon technologies Qualcomm has patented, those royalties are higher.

In a filing in January, Apple said that it had signed a five-year exclusivity agreement with Qualcomm that expired in 2016. Apple then used competing wireless modem chips from Intel (INTC) in some of its iPhones. Qualcomm has sought royalties for those iPhones, claiming any wireless modem chip relies in some way on technologies that it has patented.

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For its part, Qualcomm has said that Apple “intentionally mischaracterized” the companies’ agreements and the value of its patent technologies. Qualcomm general counsel Don Rosenberg also accused Apple in January of instigating regulatory inquiries into Qualcomm’s business.

Qualcomm’s practices are currently being investigated in the European Union and Taiwan, and South Korea has already fined Qualcomm more than $900 million for alleged anti-competitive activities. The U.S. Federal Trade Commission is also examining Qualcomm’s business dealings.

It’s not immediately clear how the latest U.K. lawsuit might impact the broader battle between the companies, and whether it could ultimately impact their working relationship.

Neither Apple nor Qualcomm immediately responded to a request for comment on the lawsuit.