The figures used by the Department of Health to play down the cost of implementing a tobacco display ban are wrong - says the company quoted in the department's own briefing notes.

The DH is lobbying peers ahead of a crucial House of Lords vote on the Health Bill set for next Wednesday. It claims the implementation of specialist covered gantries could cost retailers as little as £120, basing its figures on a quote from Canadian tobacco display specialist 4 Solution.

However, in an email to anti-smoking group ASH, 4 Solution vice president Philip Beder explained it would cost much more.

Beder said the DH quote was based on a minimum order of 1,500 units and did not include the extra cost of a locking device, shipping or installation.

He added that the system he quoted for was a temporary solution that would last for up to six months before a more permanent fixture could be installed.

In total he said the cost per store for this temporary fix would be approximately £480.

"For individual stores requiring this type of system the costs could be prohibitive due to the need for specific builds," he added.

The revelations lend further weight to the Association of Convenience Stores, which had disputed the Department of Health figures and put the cost closer to £2,000.

ACS chief executive James Lowman wrote to health minister Lord Darzi this week to express his concerns.

"We have now had the chance to understand the basis for these estimates and it is clear they have been misinterpreted by DH and the information provided to peers is highly misleading," said Lowman.

He reiterated the association's belief that the cost to individual retailers would be significant.

Should the Health Bill come into force, supermarkets would have to stop displayed tobacco products by 2011, with small stores coming into line by 2013.