MEGA-RICH Amazon is using “dirty tricks” to bust union organising, GMB charged today after it was forced to withdraw a historic push to win recognition at the online retail giant’s Coventry warehouse.

During months of groundbreaking pay strikes, the general union’s membership at the site has skyrocketed from about 60 to more than 800 — well over half the 1,400 employees that Amazon said worked there last year.

But as GMB made an official application to the Central Arbitration Committee (CAC), which can force bosses to recognise unions if they represent more than 50 per cent of the workforce, the US-owned firm “flooded” the warehouse with 1,300 new staff, the union said.

According to the Guardian newspaper, the committee has accepted the company’s evidence that as many as 2,700 people are now employed there, leading GMB to drop its recognition bid.

The union could have pushed ahead, prompting the CAC to call a ballot to gauge staff support, but if it lost such a vote, another could not take place for at least three years.

GMB senior organiser Stuart Richards slammed the company’s “immoral anti-union tactics,” saying that the move was purely in response to union membership coming so close to the threshold for statutory recognition. 

“Amazon has refused to pay workers a decent wage but are now paying an additional 1,300 workers to try and bust the union,” he said.

“We estimate that’s more than £300,000 a week just to stop workers having a voice in their workplace. 

“This is more than it would cost to pay the original workforce the £15 an hour they were asking for. It’s dirty tricks, plain and simple.”

Despite the setback, Mr Richards warned that “we’re not going away.”

A further three-day strike is due to begin in Coventry on Monday, while industrial action ballots for about 150 workers at Amazon’s Rugeley and Mansfield warehouses are due to close tomorrow. 

Just before the announcement that the recognition bid had been dropped, GMB general secretary Gary Smith told the final day of the union’s annual congress in Brighton: “Amazon – we’re coming for you.”

A company spokesperson said: “At Amazon, we regularly recruit new team members, across the country and across the year, providing great new career opportunities for thousands of people and to meet customer demand. This year is no different.”