Putting VAT back up to 17.5% will cost shopkeepers £90m, according to the British Retail Consortium, as the Conservative Party refused to rule out raising VAT further if they come to power.

Retailers spent £90m altering their prices and systems when VAT was reduced in December, and the British Retail Consortium said that it will cost a similar amount to reverse the change by next January, as the Government is planning.

Shadow chancellor George Osborne has also declined to rule out increasing VAT to rebalance public finance and according to The Telegraph senior Conservatives are looking at the possibility of increasing VAT to 20%.

Separately according to an analysis of the move’s impact on consumer prices, a third of retailers ignored the December reduction from 17.5% to 15%.

The Office for National Statistics reports that while 43% of shops applied the price change and 14% changed all prices marked on the shelves, 9% used a combination of the strategies.

The British Retail Consortium disputes the claim that shops did not pass on the cut. Says a spokesman: “Our members made a huge effort to ensure the cut happened, and we are not aware of any member who did not pass the cut on to their customers, even at the start.”