One of the most powerful trade unions in the United States has vowed to damage the reputation of “two-faced” Tesco around the world in an unprecedented attack on Britain’s biggest retailer.

The United Food and Commercial Workers’ Union (UFCW) condemned the supermarket yesterday for the way in which it treats staff in the US and said that there were stark differences with the rights and benefits enjoyed by workers in Britain. Union officials unveiling the “Two Faces of Tesco” campaign in London pledged to name and shame the retailer until its directors came to the negotiating table.

Emily Stewart, the UFCW campaign director, said: “We are not here to make mischief. We are here to make a stand for basic employment rights. Tesco’s reputation is being sullied by its behaviour in the US.”

The move represents a significant escalation in the union’s campaign for recognition at Fresh & Easy, the convenience store chain that Tesco started in America last November. The union claims that Tesco has refused to meet it over the past two years, despite letters from Barack Obama and Hillary Clinton to Tim Mason, the Fresh & Easy chief executive.

The union said that the stance could hinder Fresh & Easy’s potential expansion to cities such as New York and Chicago, which are heavily unionised. Wal-Mart, which also refuses to recognise the UFCW, has hardly any presence in either city.

The campaign was backed by John Cruddas, the Labour MP. He said that Tesco’s refusal to meet the union threatened to undermine the reputation of British companies.

Tesco’s expansion into the US has been the subject of intense scrutiny since the first store opened near Los Angeles seven months ago. Critics of the format claim that sales targets have been missed by up to 70 per cent. Tesco insists that the launch has surpassed expectations. It has more than 60 stores in California and Arizona.

The UFCW said that it felt let down by Tesco’s refusal to meet, given its partnership programme with the Usdaw shopworkers’ union in Britain. Ms Stewart said that staff in the US had no written contract and had to count sick leave as holiday.

Tesco, which announced a £92 million payout to UK staff in its company share-save scheme yesterday, said that employees at Fresh & Easy stores had no desire to join the union. A spokesman added: “The UFCW does not reflect the views of Fresh & Easy staff, who are overwhelmingly in favour of the pay and benefits they receive.”

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