Britain’s biggest private sector union is using “cyber-warfare” to open a new front in a campaign against Marks & Spencer over workers’ rights.

Unite, which has nearly two million members, plans to use searches for M&S on Google from 5am today to divert users to its list of grievances.

Anyone typing “M&S” or variations of “Marks & Spencer” into Google will see a direct link to the “Look Behind the Label” campaign put together by the T&G section of Unite, as well as normal search results.

The cost to the union of taking its views on to the global stage could be as little as £500.

Tony Woodley, the Unite general secretary, said: “The power of the internet gives unions the potential to go beyond its membership and reach out directly to millions of people and influence consumers.

For companies such as M&S, its brand is everything. A concerted campaign against a company’s behaviour can be a very effective addition to industrial action.”

Unite has been in talks with Marks & Spencer for three months over allegations of a “two-tier” workforce in companies that supply the chain with poultry and red meat.

The union claims that in an attempt to drive down costs, M&S suppliers are using agency workers on a near-permanent basis, but refusing to grant such workers, often migrants, the same conditions as full-time staff.

Unite also alleges that Marks & Spencer is not clearly labelling its meat products in order to hide supplies of cheap imports from Brazil and Thailand, despite the store’s stance as one of the most ethical in the country.

Marks & Spencer denies the union’s claims fiercely and insists that it meets all national standards.

A spokeswoman said last night: “We are extremely disappointed with the action Unite is taking.

“We are at a loss to understand why they continue to single out M&S when we have a leading position in labour standards and work very hard with all our suppliers to maintain these.”

Unite’s move reflects an increasingly flexible approach to campaigning taken by trade unions in recent years.

Two years ago the GMB union took a camel to the local church of Damon Buffini, a key figure in the private equity industry, in a protest at alleged asset-stripping of the AA by Permira, his company.

The biblical allusion suggested that it might be easier for the animal to pass through the eye of a needle than for a rich man such as Mr Buffini to get into Heaven.

Unite tested the power of the internet earlier this month by putting a short film on YouTube to highlight the plight of workers who lost their jobs last year when Lil-lets, the tampon company, shut its British factory and transferred work abroad.

Eric Lee, editor of Labourstart.org, a campaigning website for the international trade union movement, said that the internet “levelled the playing field”.

Mr Lee said: “British trade unions have lagged behind American ones in using the power of the internet, but that seems to be changing.

“It’s such a cost-effective way of reaching as many people as possible and competing with companies that have far bigger budgets.”

Unite will also hold demonstrations at nine M&S sites across Britain today.

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