New York's top financial regulator has expanded a probe into whether reinsurance companies have written policies on international trade with Iran, which could potentially violate new US sanctions.In a letter posted to its website, the state's Department of Financial Services asked reinsurers, including many Bermuda reinsurers, to explain their dealings with entities and people that have ties to Iran.The department also asked reinsurers to explain procedures in place to ensure compliance with the Iran Freedom and Counter-Proliferation Act of 2012, which took effect on July 1.The Association of Bermuda Insurers and Reinsurers (ABIR) said: “Many of our members were subject to the first data call; the companies are filing their responses by the July 26 deadlines. ABIR members are subject to both US and EU sanctions regimes. Companies have compliance plans in place.”Twenty reinsurers are getting the letter, including Hannover Re, Lloyd's of London and Swiss Re, Reuters reported, citing a person familiar with the matter said.A spokesperson for XL in Bermuda told The Royal Gazette: “I can confirm that some XL companies have been contacted by the New York Department of Financial Services (DFS) and they are preparing to file responses by the requested deadline.”It’s understood the Corporation of Lloyd’s did receive the letter as indicated in published reports and is responding on behalf of all syndicates.Superintendent Benjamin Lawsky opened his probe after news reports that Switzerland-based Glencore Xstrata Plc and Trafigura AG had supplied thousands of tons of alumina to an Iranian firm that provided aluminum for Iran's nuclear programme.The new law bans financial services companies that do business in the United States, such as insurers and reinsurers, from providing services to companies that trade with Iran.Such a ban can make it harder for shippers to transact with Iran, because they need insurance to protect against the risk of losses on big shipments.