China's Huawei Technologies, which for years has denied violating American trade sanctions on Iran, produced internal company records in 2010 that show it was directly involved in sending prohibited US computer equipment to Iran's largest mobile-phone operator.
Two Huawei packing lists, dated December 2010, included computer equipment made by Hewlett-Packard and destined for the Iranian carrier, internal Huawei documents seen by Reuters show.
Another Huawei document, dated two months later, stated: "Currently the equipment is delivered to Tehran, and waiting for the custom clearance".
The packing lists and other internal documents provide the strongest documentary evidence to date of Huawei's involvement in alleged trade sanctions violations. They could bolster the US government in Washington's campaign to check the power of Huawei, the world's leading telecoms equipment maker.
"Due to ongoing legal proceedings, it is not appropriate to comment at this time," a Huawei spokesman said. "Huawei is committed to comply with all applicable laws and regulations in the countries and regions where we operate, including all export control and sanction laws and regulations of the UN, US, and EU."
The US is trying to persuade allies to avoid using Huawei equipment in 5G mobile systems. Separately, US authorities are battling Huawei on a legal front.
The documents involve a multi-million dollar telecommunications project in Iran that figures prominently in an ongoing criminal case Washington has brought against the Chinese company and its chief financial officer, Meng Wanzhou who is the daughter of Huawei's founder.