Taxi drivers are ramping up a campaign for better pay and union recognition from Addison Lee by challenging the company’s major corporate clients to uphold commitments signed under a UN accord obliging them to use ethical suppliers.

Deutsche Bank is the first of the taxi company’s clients to be approached by union representatives who have also pointed out that its own “vender code of conduct” obliges it to recognise the right to collective bargaining, and minimum and prevailing wages and benefits.

They plan to write to the UN secretary general asking for the bank to be kicked out of the UN Global Compact, which is billed as the world’s largest corporate sustainability initiative. Signatories commit themselves to upholding universal principles including human rights and labour.

Other companies using Addison Lee, such as KPMG and Credit Suisse, are also likely to be challenged as part of a new tactic by trade unionists in the frontline of the battle over gig economy jobs.

“We think it is outrageous that these companies brandish these great codes of conduct as a way of enhancing their reputations,” said James Farrar of the United Private Hire Drivers branch of the Independent Workers Union of Great Britain.

“But if it means nothing in Britain then how can we expect it to be respected in a developing country with already low levels of respect for the rights involved?”

A Deutsche Bank spokeswoman said it worked with various private car hire companies in the UK and had only a small share in Addison Lee’s turnover. “Our contracts with Addison Lee as well as the agreed rates are in line with current market standards in the industry. We have engaged with Addison Lee on the issues and they confirmed to us that they comply with all relevant legislation,” she said.

A spokesperson for Addison Lee said: “Addison Lee Group takes its responsibility to provide a fair and flexible environment for its 5,000 driver partners very seriously. As a result, earnings are at a record high and over 60% of drivers said they were likely or very likely to recommend working for Addison Lee in our most recent driver satisfaction survey.

“In common with most of the private hire and taxi industry, the majority of our drivers are self-employed.”

The development comes against the backdrop of an ongoing issue between Addison Lee and drivers taking passengers to and from Luton airport, where the concession for operating services was sold to the company by Luton council in 2016.

The union is advocating on behalf of Addison Lee drivers who saythe company has been insisting on increased commissions on fares – up to 35% in the case of drivers servicing Luton airport. Vehicles rentals have increased to as much as £270 a week while drivers working 70 hours a week are earning less than £5 an hour, according to the union.

Frank Field, the MP and chairman of the work and pensions select committee, is to write to Luton council and Addison Lee to express his concerns after taking evidence from more than two dozen drivers.