Britain’s Export Control Organization told a London court Thursday that it would not release information on the names of companies in the UK that do business with Iran, because of fears that the United States could pressure the banks those companies do business with to cut the companies off as customers, as required by U.S. law.

The ECO was responding to a lawsuit by Bloomberg News that asked for the information to be released under Britain's “sunshine laws,” which requires government agencies to report certain types of information. The lawsuit dates to 2009, when the U.S. Bloomberg business news channel asked the British Department for Business, Innovation and Skills, or BIS, which oversees the export agency, to release information on which companies had applied for a permit to do business with Iran in the first half of 2009. BIS denied the request, which Bloomberg first made as part of an investigation into several Iranian plane crashes.

Under U.S. law, any entity that does business with Iran could be subject to sanctions, which could include fines or a ban from doing business with American companies in the U.S. Even without specific sanctions against banks, British officials said, the prospect of possible problems with the U.S. State Department would be enough to discourage investors or clients to cut ties with the banks in question.

In an affidavit supporting the British government's position in the lawsuit, the British-Iranian Chamber of Commerce, which promotes trade between Tehran and London, said that “publicity in newspapers brings our members, who undertake legal trade with Iran, to the attention of the U.S. authorities, who pursue them, and to their own banks, who withdraw banking facilities.” The banks, in response to U.S. pressure, go on a “witch hunt,” the organization said, rooting out companies that have connections with Iran, in order to avoid finding themselves being investigated and sued by the U.S. government for failing to comply with sanctions.

In its filing, Bloomberg said that the British respondents were exaggerating the possibility of problems with U.S. authorities, and that the information was relevant to its investigation. “The U.K. is one of the largest manufacturers and exporters of civil aviation parts in the world,” the news organization told the court. “It was of public interest to know whether U.K. companies were applying to export such products to Iran and were being denied. There is a public interest in safe civil aviation wherever a person may be traveling.”