An official complaint about Sadiq Khan has been raised amid a row over City Hall striking a deal with an airline for flights to and around the USA.
It came as fresh details emerged of the agreement made between the mayor’s office and United Airlines, which allowed Mr Khan, his team and a group of journalists to travel on the cheap.
The five day trip in May 2022 - which included visits to New York, San Francisco and Los Angeles - was a mayoral trade mission, intended to draw American tourists, business and investment to London.
But critics have raised questions about the fact that flights for the entire party were provided free by United Airlines, with only fees and taxes payable, and whether anything was given by City Hall in exchange.
The mayor’s office argues that the deal was not a "formal partnership" and that Mr Khan "make no apologies" for "saving taxpayers money on the flights".
In a formal complaint to City Hall’s monitoring officer however, Green assembly member Caroline Russell said she was concerned about a lack of openness and integrity from the mayor.
She said this was partly because of posts sent by Mr Khan’s personal and official Twitter accounts, which appeared to promote the airline during the visit.
London is an unrivalled location to visit and invest in. I’m excited to take this message to New York, San Francisco and Los Angeles and showcase our amazing city to America.
— Sadiq Khan (@SadiqKhan) May 8, 2022
First stop NYC - with @United - who are now flying 22 times a day from Heathrow to the US. 🇺🇸🇬🇧 pic.twitter.com/HLi3lx1pRh
A line was also inserted into City Hall’s press release about the trip, which read: "United Airlines is proud to be flying the Mayor of London Sadiq Khan and his team on their trade mission to the United States. United Airlines is set to operate 22 flights per day from London Heathrow to the United States for Summer 2022."
Ms Russell’s complaint is currently being investigated.
The mayor’s chief of staff, David Bellamy, admitted during a London Assembly meeting in June that it is "a natural part of these trips that businesses doing business with London get some publicity out of it", but he said he "would not describe it as a United Airlines sponsored trip".
A document seen by the Standard shows how City Hall agreed that in exchange for the flights - which were mostly in business class - the airline could receive several "promotional opportunities".
These are listed on the document as "recognition" by Mr Khan "at external events across the three cities", as well as being "where and whenever appropriate, invited to join the Mayoral events during the May visit" and for the "United logo to be included on event signage as/where appropriate".
In addition, it was agreed that United would "liaise with the Mayor’s office to optimize all appropriate PR opportunities" and would have the right to pre-approve all materials issued by City Hall which used United’s name or logo.
However, it is not known whether all of these benefits were enjoyed in reality by the airline.
The agreement also covered "the travelling press". This enabled City Hall to invite journalists, including from the Standard, BBC, ITV and other outlets, to join and report on the trip without those organisations having to pay air fares.
Ms Russell told the Standard: "The office of the Mayor of London should not be for sale – yet, United Airlines secured free publicity and final sign-off of mayoral materials in exchange for business class flights to the United States.
"London's mayor is bound by the principles of public life outlined in the Code of Conduct, and I am concerned the integrity of his office has been tarnished by what appears to be the endorsement of a product that actively harms the very people he was elected to serve.
"Londoners wouldn’t like BP’s logo on the mayor’s SUVs, they wouldn’t like Nestle sponsoring free school meals, and they won’t like a corporate polluter getting a publicity boost from their mayor in exchange for free flights abroad."
She added: "Ultimately, this so-called ‘partnership agreement’ lacks the integrity and transparency we expect from City Hall. Londoners deserve to know what other polluters might be able to buy their mayor’s endorsement."
A spokesman for Mr Khan said: "Promoting London at home and abroad is a key part of the mayoralty and Sadiq makes no apologies for travelling to the US last year and saving taxpayers money on the flights.
"This visit was his first international mission since the start of the pandemic and an opportunity to encourage tourism to London and showcase the capital to businesses, investors, entrepreneurs and students in the world’s largest economy.
"In order to reduce the cost of the visit, City Hall secured an agreement for a group flight package with United Airlines, where only taxes and fees were payable.
"This one-off agreement did not result in a formal partnership between the Greater London Authority and United Airlines."
A United Airlines spokeswoman said that the company has made a number of sustainability-related announcements this year, including a goal of using 10 million gallons of sustainable aviation fuel in 2023 – about three times more than 2022 and 10 times more than in 2019.
