Postcard plea for Big Four

The organisation is seeking the adoption of a new rule forcing multinational companies to report tax results country by country in a bid to prevent tax evasion. The NGO estimates evasion costs developing countries $160bn (£106bn) a year in lost revenue.

Around 80,000 Christian Aid supporters are being encouraged to contact the heads of the Big Four firms.

Barry Marshall, UK head of tax at PricewaterhouseCoopers, said the firm met with Christian Aid at the end of last year, prior to the start of the postcard campaign.

‘We have a common interest to improve corporate reporting of tax information. However, we do not believe the introduction of the kind of country-based reporting proposed by this campaign would meet this ambition,’ he said.

Judith Cavanagh at Christian Aid, said: ‘Minimising tax, whatever the social consequences, has, in recent years, gained a spurious respectability which they [the Big Four] could help puncture.’

Spokespersons for Deloitte and E&Y refused to comment. KPMG had not commented at the time of going to press.