(Reuters) -British drugmaker GlaxoSmithKline sued Moderna ( MRNA ) in U.S. federal court in Delaware on Tuesday, accusing its American rival of violating GSK's patent rights in messenger RNA (mRNA) technology with its blockbuster COVID-19 vaccine Spikevax.

According to the two lawsuits, Moderna's ( MRNA ) lipid nanoparticles for transporting fragile mRNA into the human body infringe several GSK patents covering similar innovations. GSK filed a related lawsuit against Pfizer ( PFE ) and BioNTech in the same court in April over their COVID-19 vaccine. The new litigation seeks unspecified monetary damages.

A Moderna ( MRNA ) spokesperson said the company was aware of the new litigation and would defend itself against the claims. A GSK spokesperson said the drugmaker is "willing to license these patents on commercially reasonable terms and to ensure continued patient access."

The lawsuits add to a web of U.S. court cases involving Pfizer ( PFE ), BioNTech and Moderna ( MRNA ) over patent royalties for technology used in their vaccines, including one brought by Moderna ( MRNA ) against Pfizer ( PFE ) in 2022.

Moderna ( MRNA ) earned $6.7 billion in revenue from Spikevax last year. Pfizer ( PFE ) made $11.2 billion from sales of its and BioNTech's vaccine Comirnaty. Sales of both vaccines declined significantly last year from 2022.

GSK said in the new litigation that its patents cover mRNA technology pioneered in 2008 that provides "the foundation for Moderna's ( MRNA ) mRNA vaccine portfolio." GSK said it bought the rights to the inventions when it acquired part of Novartis' vaccine business in 2015.