The measure in question, H.R. 1985, which was introduced in April by Rep. Mark Kirk, R-Ill., amends the Iran Sanctions Act of 1996 and would expand economic sanctions against Iran.

Part of the measure calls for sanctions against those engaged in an activity that could contribute to the enhancement of Iran's ability to import refined petroleum resources, or provide Iran with goods, services, or technology for refining petroleum.

It targets suppliers, brokers, insurers and [oil] tankers, "including Lloyds of London, Total (France) and British Petroleum unless they end their involvement in the export of refined oil to Iran or the construction of refineries in that country," Realite-EU said.

But Bart Nash, a spokesman for Lloyd's, when asked about Realite-EU comments, said when coverage is arranged for a ship such as an oil tanker "you insure a ship over the course of a year" and that "an insurer doesn't know what a ship will be carrying nine months down the track."

Speaking for the corporation he said, "We are unaware of any businesses at Lloyd's defying international sanctions. If we discovered any underwriters breaching sanctions we would take action immediately."

Also a lawyer with knowledge of Lloyd's operations said the market is not materially involved in cargoes and noted that insurance and reinsurance is sold on a fleet basis, and annually, not on a per-cargo or per-country basis. So "the underwriter is not aware of any particular voyage or any particular destination."

The Kirk bill is one of a number of measures introduced to give the president tools to pressure Iran. So far none have been taken up by Congress including legislation sponsored by Howard Berman, D-Calif., chairman of the House Foreign Relations Committee.

Realite-EU noted U.S. authorities in the past have taken action against British financial institutions for ignoring Iranian sanctions.

It mentioned that in January a British bank, Lloyd's TSB (that is unrelated to Lloyd's of London), agreed to forfeit $350 million (?231million) in a plea agreement with the U.S. Department of Justice.

Lloyd's TSB admitted then to a single charge of violating the U.S. International Emergency Economic Powers Act. The bank will serve a form of probation for two years.

The sanctions violated by Lloyd's TSB involved falsifying wire transfers to disguise their origin and channeling Iranian and Sudanese money into the American banking system between 1995 and 2007, said Realite-EU.