Horror writer Stephen King has sued his insurance company for $10m (£6.25m), claiming it failed to provide full coverage for injuries he suffered when a van hit him in western Maine two years ago.

King filed the lawsuit against Commercial Union York Insurance, which has branches in Portland and Bangor and is a subsidiary of CGNU, last week in Penobscot County Superior Court.

He and his wife, Tabitha, will seek the umbrella policy's $10m limit plus interest of 1.5% per month, said their lawyer, Warren M Silver of Bangor, who said the figure fell well short of King's physical and financial damages.

“He has had some very significant problems and continues to have them,” Silver said.

“He is having trouble, but has been able to deal with the pain, and continues to work because he is such a strong and focused person.”

King, 53, was injured in June 1999 when a van driven by Bryan Smith of Fryeburg struck the author as he was walking along the shoulder of Route 5 near his vacation home in Lovell.

He suffered a broken leg and hip, punctured lung, broken ribs and other injuries. He has undergone five operations since the accident, and Silver said another operation would probably be performed this summer.

Lawyers for Commercial Union York said it had paid King a $450,000 (£281,000) payment under his motor and homeowner's policy.

A statement from the law firm Norman, Hanson & Detroy rejects King's argument that he is entitled to further payments under his umbrella cover beyond the $450,000 already paid.

The firm said: “The umbrella endorsement is designed to cover King's liability to others. It expressly excludes personal injury caused by an underinsured motor vehicle.”