Top retailers including Welcome Break, Morrisons and Spar are supporting a letter to be sent to George Osborne tomorrow, asking the government to take action on increasing card transaction charges that are costing both big and small retailers dear.

The campaign, which is being spearheaded by CMS Payments Intelligence, will see more retailers register their support at an event at the House of Commons tomorrow.

The event coincides with the EU General Court’s verdict on MasterCard’s appeal against the European Commission’s decision that the way interchange rates are set on European cross border credit and debit card payments is unfair and anti-competitive.

If the ruling favours MasterCard, then the costs to retailers and all businesses where customers pay by card are likely to increase significantly.

If the ruling goes against MasterCard, as CMS Payments Intelligence hopes, then it should lead to regulation of domestic interchange rate, saving UK retail businesses hundreds of millions of pounds.