Transport for London (TfL) will be referred to the advertising watchdog for displaying anti-Tory advertising during the election period.

Israeli tech startup Monday.com has paid for advertising on the Tube that makes fun of Boris Johnson’s background and his record as mayor of London and Prime Minister.

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Each advertisement is presented as a to-do list, with one making fun of Johnson’s schooling at Eton College and another of the Conservatives’ failure to complete Brexit.

One focuses on the failed £53m Garden Bridge project the former mayor of London spearheaded.

It reads: “Set up charity, £5.4m – done. Outsource to French, £21.4m – done. Cancel construction, £26.7m – done.”

TfL’s guidelines say advertisements on the Tube should not promote party political causes or electioneering slogans.

The guidelines say that the body should be particularly careful during election periods.

Shaun Bailey said it was clear the advertisements were in breach of TfL’s guidelines and that he would be referring the matter to the Advertising Standards Authority (ASA).

“Our transport system mustn’t become a partisan canvas during pre-election periods,” he said.

“As the chair of TfL, the mayor [Sadiq Khan] should give a full and proper accounting regarding the decision making around this possible breach of TfL rules.”

However, TfL said the advertisements did not breach policy guidelines and were launched before the election was called.

A spokesperson said: “The campaign currently running was approved at the beginning of October and is due to finish on 1 December, with the removal process starting this week.”

A spokesman for the mayor also said there was no case to answer for as TfL has said the advertisements were not in breach of their own guidelines.

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A Labour source suggested it was unwise for Bailey to push the issue.

They said: “It’s very brave of the official Tory candidate for London Mayor to amplify so loudly the failures of Boris Johnson, including Brexit and the Garden Bridge.”