(Reuters) - Apple Inc has been hit with a proposed class action lawsuit claiming that its first-generation through Series 6 Apple Watches have a defect that make their screens prone to breaking or detaching, in some cases injuring wearers. The lawsuit, filed by five individuals in San Francisco federal court on Thursday, claims that the lithium batteries in the popular wearable fitness trackers are prone to swelling, leading to the screen failures. The complaint includes a picture of a deep laceration on the arm of one plaintiff, allegedly suffered when his screen broke. The plaintiffs claim that the defect has been present in various versions of the Apple Watch and that it knew of the risk but concealed it from consumers. They said the insufficient space to allow for battery swelling "poses a material and unreasonable safety hazard to consumers," and are bringing claims on behalf of Apple Watch purchasers under federal and California consumer protection laws. Apple did not immediately respond to a request for comment. Apple was hit with a lawsuit making similar allegations of screen defects in the same court, represented by different counsel, in 2018, although it did not directly link the screen defects to swelling batteries. A federal judge in 2019 dismissed that case, finding that the plaintiff failed to identify a specific defect. Another such case, filed in New Jersey federal court in 2019, did link the defect to swelling batteries. A federal judge allowed part of that lawsuit to proceed, but the plaintiff in 2020 moved to drop it, without giving a reason. The case is Smith et al v. Apple Inc, U.S. District Court, Northern District of California, No. 3:21-cv-09527. For plaintiffs: Michael Ram of Morgan & Morgan