Microsoft is demanding $6.9 million interest from Samsung Electronics in a dispute over smartphone patent royalties, according to a lawsuit unsealed by a New York federal court on Friday. Microsoft is asking the court to rule that it did not breach a business collaboration agreement with Samsung, and that Samsung must pay interest on more than $1 billion in royalty payments which it delayed in protest at Microsoft's planned purchase of rival Nokia's handset business.

Samsung made royalty payments on time to Microsoft during the first fiscal year after they signed their 2011 agreement, the lawsuit said.

However, after Microsoft announced the Nokia deal in September 2013, Samsung initially refused to make another payment, arguing that the Nokia deal breached its licensing agreement with Microsoft. It eventually paid late without adding interest, according to the lawsuit.

Samsung has been paying Microsoft $1 billion a year in royalties to use its technology in Samsung’s Android smartphones and tablets, according to the court document.

The filing also shows that Microsoft offered to reduce Samsung’s payments if it developed Windows tablets and phones alongside its Android products.

Samsung is one of 25 companies that pay Microsoft to use its technology in Android products.