Boris Johnson has drawn widespread condemnation for allowing London to host the world's biggest arms fair that senior London politicians have warned is "promoting an industry that thrives on the kind of death and destruction we are witnessing in Syria".
The London Mayor has also been accused of offering "feeble excuses" to justify allowing Syria's Russian state arms supplier to attend the fair, which opened on Tuesday at London's Excel centre.
London politicians have called on the Mayor to lobby ministers to revoke Russia's invitation rather than allowing "an arms manufacturer that has sold weapons to the brutal regime in Syria now turning up in London to sell more weapons to other brutal regimes around the world".
The "Defence Security Equipment International" (DSEI) fair brings together 1,500 international exhibitors from more than 50 countries, including the United Arab Emirates, India, Russia and the United States.
Nearly 30,000 people from the arms industry are expected to attend the fair, which is supported by the Ministry of Defence and UK Trade & Investment (UKTI).
Labour Assembly Member John Biggs said: "I have long argued that Excel should not be home to an arms fair. While the reality of life is that arms are a necessary evil their display in a city centre location identified mainly with leisure activities trivialises a deadly issue and offends me and I think many other Londoners."
The London Mayor told HuffPostUK that Britain's involvement in the arms trade was useful as it was "sensible" as a way to provide "legal weaponry" to governments, with Britain "an expert at making some of them".
The Mayor told HuffPostUK: "This is an argument that is centuries old and thankfully global conflicts are diminishing in number, but insofar as it is necessary for governments and authorities to be properly equipped against those who mean them and their people harm, it is only sensible to have legal weapons. It so happens that this country is an expert at making some of them."
Green assembly member Jenny Jones told the Huffington Post UK: "The Mayor should focus on what is moral, rather than what is legal.
“I’ve been inside this event to take a look for myself and I think it shames London. Promoting an industry that thrives on the kind of death and destruction we are witnessing in Syria is not a good thing."
"The government should end its subsidies for the arms industry. I hope this is the last arms fair ever held in London."
Arms campaigners have also rounded on the Mayor. Kaye Stearman, from the Campaign Against The Arms Trade, said: "Boris Johnson has a reputation for making outrageous remarks and this lives well up to his usual standard. The UK's involvement in the arms trade is not sensible but stupid."
The attendance of Russia's state technology firm 'Rostec' has sparked heightened fury, as its export company Rosobronexport has supplied weapons to the regime of Syrian president Bashar Al-Assad.
The Mayor avoided condemning Rostec's presence, telling HuffPostUK: "Well, you know. It's very important that there should be access to legal weapons. As far as I understand it, there is no question of illegality and this is an argument that is of great antiquity."
Despite the Mayor's reluctance to criticise the presence of Russia for its links to the Syrian regime, he branded the parliamentary vote against military intervention in Syria as a "great shame".
LibDem assembly member Stephen Knight told the Huffington Post UK that the Mayor's "feeble excuses" for allowing Rostec's presence were "deeply disturbing".
"I find it deeply disturbing that the Mayor of London cannot find anything wrong with an arms manufacturer that has sold weapons to the brutal regime in Syria now turning up in London to sell more weapons to other brutal regimes around the world," he said.
“Instead of providing feeble excuses the Mayor should be using his influence to ensure our government immediately revokes their licence to attend and for the conference organisers to cancel their conference place.”
HuffPost UK contacted City Hall but they have declined to comment