Shares in insurance firm Royal & Sun Alliance fell on Thursday after General Motors reportedly filed a lawsuit against the UK insurer in the United States, seeking multi-million dollar payment of asbestos-related claims, Reuters said.

A spokesman for the UK insurer told the news agency it had not yet seen the lawsuit but said its US unit Royal USA had filed on Wednesday for a declaratory judgement that it had no duty to defend or indemnify the US automaker from claims related to asbestos, a cancer-causing mineral fibre that was used in a wide variety of products.

"We don't believe there is an entitlement to coverage," the spokesman told Reuters.

The news agency said the Financial Times newspaper reported that in the lawsuit GM alleges that RSA had refused to pay claims against GM for alleged personal injury associated with asbestos and alleged property damage associated with environmental contamination - the claims relate to liability polices Royal & Sun's US units wrote between 1954 and 1971.

The newspaper reportedly said that GM names Royal & Sun, the parent company, as well as its US subsidiaries in the lawsuit but no figure was put on the claims or damages it was seeking.

By 1035 GMT on Thursday, shares in Royal & Sun had sunk 2.32% to 84-1/4 pence each, Reuters said.