Tokyo Electric Power's bill for its Fukushima nuclear disaster may swell as more United States military personnel join a lawsuit charging the utility with lying about radiation levels they faced while assisting relief efforts after Japan's 2011 earthquake and tsunami disaster.

Twenty-six plaintiffs refiled a suit this week, with as many as 100 others in the process of joining the legal action, in demands for more than US$2 billion in compensation, the Stars and Stripes newspaper reported on Saturday, citing attorneys. An initial complaint was filed on December 21 by eight sailors.

The amended suit filed in California seeks at least US$40 million in compensatory and punitive damages for each plaintiff, as well as a fund exceeding US$1 billion, up from an earlier demand for US$100 million, for monitoring health and payment of medical costs, according to the report.

Tepco, as the Japanese utility is known, and the Japanese government conspired to create the false impression radiation leaking from the Fukushima Dai-Ichi plant did not pose a threat to the sailors, according to the original complaint. As a result, the plaintiffs rushed into areas that were unsafe and too close to the power plant, exposing them to radiation, the sailors' lawyers said.

Tokyo was "lying through their teeth about the reactor meltdown" as it reassured the crew of the USS Ronald Reagan that "everything is under control", the plaintiffs' lawyers said in the December complaint. "The plaintiffs must now endure a lifetime of radiation poisoning and suffering."

Tokyo Electric "confirmed" changes, including an addition to the number of plaintiffs, were made on March 12 to a lawsuit originally filed with the US District Court for the Southern District of California, the utility said in a filing to the Tokyo Stock Exchange.

Tepco "has not formally received the written complaint as of March 15", it said in the filing. "Once the complaint is formally delivered to us, we will handle the case appropriately after reviewing the plaintiffs' claims and demands," the firm said.