Terrorists linked to Iran were caught by intelligence officials stockpiling weapons near London.

Radicals linked to Hizbollah, the Lebanese militant group, stashed hoards of disposable ice packs containing ammonium nitrate, an ingredient commonly used to make home made bombs.

The plot was uncovered by MI5 and the Metropolitan Police in 2015 but the public and MPs were kept in the dark, according to The Daily Telegraph.

Over one-thousand new recruits of the guerrilla movement Hizbollah listen to a speech by their leader Sheikh Hassan Nasrallah during a ceremony held in Beirut November 11, 2001

Three tonnes of the dangerous substance was found in its raw form and police eventually arrested one man on suspicion of plotting terrorism - but released him without charge.

His identity was kept secret, as were the whole findings until now - possibly in an effort to keep the Iran nuclear deal of 2015 alive.

According to the Telegraph David Cameron and Theresa May, then the prime minister and home secretary, were personally briefed on what had been found in the sites on the edge of the capital because it may have pointed to a large terrorism threat to the UK.

Ben Wallace, the security minister, told the paper on the subject of the public not knowing about the plot: 'The Security Service and police work tirelessly to keep the public safe from a host of national security threats.

'Necessarily, their efforts and success will often go unseen.'

Hizbollah Deputy Secretary General Naeem Kassem speaks in an interview with Reuters on Tuesday, January 20 2004 a day after Hizbollah guerrillas killed an Israeli soldier at the border

MI5 agents and officers from the Metropolitan Police's Counter Terrorism Command launched a covert operation in a bid to find out more about the operation, following a tip-off from a foreign government.

Sources told the paper that the pattern of behavior from those linked to the group suggested a wider operation, after a similar find was made in Thailand and a New York-based member appeared to seek out a foreign ice pack manufacturer.

No target had been selected and no attack was imminent, sources told the Telegraph of the plot - which appeared to be in its infancy - when disrupted by officials.

Well-placed sources said there was no evidence Britain would have been the target, the paper reported.

On September 30, the Met used search warrants to raid four properties in North London, leading to the sole arrest, this is despite sources claiming that at least two other individuals were involved.

A UK intelligence source said: 'MI5 worked independently and closely with international partners to disrupt the threat of malign intent from Iran and its proxies in the UK.'