Individuals linked to Hezbollah were caught stockpiling more than three tonnes of ammonium nitrate, a common ingredient in homemade bombs, in a factory located north-west London, Britain's MI5 discovered in 2015 based on a tip from a foreign intelligence agency.

However, the plot was kept under wraps without being disclosed to the public as it took place just months after the UK had joined the U.S. and other world powers in signing the Iran nuclear deal, The Daily Telegraph reported on Sunday.

“It raises questions about whether senior UK government figures chose not to reveal the plot in part because they were invested in keeping the Iran nuclear deal afloat,” the paper said.

According to the newspaper, the intelligence services raided four properties where thousands of disposable ice packs containing ammonium nitrate were found. A man in his forties was arrested on terrorism charges, but was later released.

The newspaper quoted “well placed sources” as saying that “the plot had been disrupted by a covert intelligence operation rather than seeking a prosecution.”

The Daily Telegraph said that the plan was part of a bigger Hezbollah attacks scheme, noting foiled Hezbollah operations in Thailand, Cyprus and New York.

In 2015 in Cyprus, the report pointed out, Hezbollah agent Hussein Bassam Abdallah was sentenced to six years in jail after 8.2 tons of ammonia nitrate stored in ice packs were found in his home.

“MI5 worked independently and closely with international partners to disrupt the threat of malign intent from Iran and its proxies in the UK,” a UK intelligence source told the newspaper.