Virgin Mobile has entered the row over mobile top-up margins, slamming competing networks as greedy.

A spokesman said: “We really symphasise with retailers and the way they are being treated by parts of the industry.”

Virgin would continue to offer paper vouchers including the £5 one as they were popular with young customers, he said.

Vodafone has provoked fury among independents with plans to replace paper vouchers with e-vouchers at a reduced level of commission.