Brokers Marsh & McLennan are being sued for “deliberately and negligently concealing” the extent of likely asbestos claims when it placed general liability policies in the Lloyd's marketplace for US manufacturers of asbestos products.

The complaint, filed on May 22 at the New York State Supreme Court, amends an earlier lawsuit filed against Marsh in November 1999.

The plaintiffs – 104 Lloyd's members from Canada, the UK and the US who participated in syndicates that insured or reinsured US policyholders from 1977 to the present – are seeking initial damages totalling $150m, plus punitive damages and costs.

A Marsh representative said it was the firm's policy not to comment on pending litigation.

The only corporate plaintiff listed in the suit is RHM Outhwaite (Underwriting Agencies), a Lloyd's managing agency that went out of business at the end of 1992 as result of asbestos-related losses.

In addition to Marsh & McLennan, the defendants listed in the suit are Marsh, Guy Carpenter, CT Bowring, Winchester Bowring and Sedgwick.