Sadiq Khan has told organisers of the world’s largest arms fair to move it out of London as protests mount over the “abhorrent” event.

Almost 100 people have so far been arrested at demonstrations against the Defence and Security Equipment International (DSEI) fair, which will open at the ExCeL centre on Tuesday.

It will see arms manufacturers market their wares to international delegations from Saudi Arabia and other nations who continue to bomb Yemen, which has become the world’s worst humanitarian crisis.

The British government has invited Saudi representatives to DSEI, despite judges ruling the sale of weapons used in the conflict unlawful in an ongoing court battle.

Ministers are to give speeches and meet foreign military officials, while the UK armed forces hosts delegates in pavilions surrounded by rockets, tanks, jets, grenades and ammunition.

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In a letter to the director of DSEI, seen exclusively by The Independent, Mr Khan said the biennial event was opposed by campaigners and Londoners who do not want weapons to be traded in their city.

“I too strongly oppose this event taking place in London,” the Labour mayor said.

“London is a global city, which is home to individuals who have fled conflict and suffered as a consequence of arms and weapons like those exhibited at DSEI.

“In order to represent Londoners’ interests, I will take any opportunity available to prevent this event from taking place at the Royal Docks in future years.”

He told organisers to “reconsider hosting the fair in London in future” and cover the costs to the Metropolitan Police.

Policing protests at DSEI 2017 cost the force almost £1m in total, including £823,750 in officers’ pay, £154,100 in overtime and £20,073 in “direct costs” such as vehicles and food.

More than 2,800 police officer shifts were needed to cover the 12-day operation.

A total of 98 demonstrators have so far been arrested during protests that started last week against this year’s DSEI fair, and Scotland Yard said a “proportionate policing plan” was in place.

Andrew Smith, of the Campaign Against Arms Trade group, accused police of being “heavy-handed” in their response to demonstrators blocking a road into the venue.

“The best way for the government to cut the policing cost would be to shut down DSEI,” he told The Independent.

“It is very welcome to see such a prominent politician making a strong statement. DSEI is a moral disgrace and should be firmly opposed, whether it is taking place in London or anywhere else.

“It will bring a roll call of the world’s most repressive regimes together with all of the biggest arms companies. They will be there for one reason: to sell as many weapons as possible, regardless of the consequences.”

The event is supported by the Ministry of Defence and the Department for International Trade, which has a wing dedicated to arms exports.

British defence giant BAE Systems is listed as a “platinum partner” alongside American firm General Dynamics, while the United Arab Emirates will have its own pavilion.

The country is part of a Saudi-led coalition bombing Yemen in a campaign that has killed an estimated 8,000 civilians and driven a deadly cholera outbreak and famine.

Government figures show that export licences worth £6.2bn have been granted to members of the Saudi-led alliance in the four years since the conflict began in March 2015.

In a letter to the Royal Docks Management Authority, which runs the ExCeL, Mr Khan said he was “opposed to London being used as a marketplace for the trade of weapons”.

The local authority, Newham Council, also opposes DSEI being held at the conference centre and is holding an “alternative peace exhibition” hosting campaigners and politicians on Tuesday.

Rokhsana Fiaz, the mayor of Newham, called the arms fair “abhorrent” after the council passed a motion “rejecting the economic arguments cynically deployed in defence of this trade”.

The DSEI arms fair in London, 2017 (Lizzie Dearden)

“Newham is a very diverse borough and many of our communities have links across the globe to those areas that have been affected by conflict, displacement and the horror of war,” she said.

“This council is doing everything we can to prevent the DSEI coming to Newham ever again.”

In a response to Mr Khan’s letter, DSEI event director Grant Burgham said it “plays an important role in supporting the Ministry of Defence’s procurement needs, helping deliver British jobs and economic growth, and deepening the UK’s partnerships on a global stage”.

“The event serves only the interests of the legitimate defence and security industry, which is the most highly and tightly regulated in the world,” he added.

“Government agencies responsible for enforcing the law at DSEI are on site during setup and throughout the exhibition.”

Mr Burgham said all security costs incurred as a direct result of the event would be met by DSEI, and that organisers “fully respect the right to lawful protest”.

The government is fighting a Court of Appeal ruling that found its continued licensing of weapons to Saudi Arabia “irrational and therefore unlawful” in June.