The Government was today accused of producing "defective" figures for how many people are sleeping rough.

The official nightly "snapshot" figure of 498 is wildly inaccurate because hundreds of councils which estimate they have up to 10 homeless on the streets are simply ignored, according to the Tories.

Shadow housing minister Grant Shapps said the true level should be nearly three times higher at more than 1,300.

The Department for Communities and Local Government (DCLG) produces figures by asking local authorities to either count or estimate how many people are sleeping rough on a given night.

However, the latest data from June shows that 271 councils estimated they had 0-10 individuals on the streets. All of these submissions were automatically rounded down to zero by officials in Whitehall.

Mr Shapps said that the figures were "defective" as a result, and insisted more accurate counting for those councils would boost the snapshot level to 1,322.

Homeless charities claim the real rough sleeping figure for a year is around 10 times higher than the nightly snapshot - meaning there could be more than 13,000 people on the streets.

"This report exposes a major hole in the collection of rough-sleeping data which means hundreds of hidden homeless people are sleeping on our streets every night," Mr Shapps said.

"The Government has downgraded the Rough Sleepers Unit because the defective data suggested the problem had largely been resolved.

"I'm calling on the Government to recognise the scale of the problem and put measures in place to work with charities and other support services to urgently deal with this unacceptable situation."

However, a DCLG spokeswoman dismissed the Tory claims as "completely misleading".

"A leading homelessness charity, Thames Reach, has already said it's ludicrous to suggest 13,000 people sleep rough each year.

"Rough sleeping has dropped substantially compared to the late nineties as a result of the Government's major investment and work on the issue."

The spokeswoman added: "The rough sleeping count methodology was worked out with the voluntary sector and is a useful snapshot of rough sleeping which captures changing levels of rough sleeping and allows meaningful comparisons between different areas.

"The Government has been working with the voluntary sector over the last six months on how assessments of homelessness can be improved, as part of the next steps to reduce homelessness and rough sleeping."

Jeremy Swain, chief executive of Thames Reach, said Mr Shapps raised "legitimate concerns", but he believed rough sleeping counts were "broadly accurate".

"It is very important that the figure of 498 people sleeping rough is understood as being a single night snapshot of the rough sleeping population.

"We know that in London alone, because people move on and off the streets, around 3,000 people will sleep rough over a year.

"Whichever way the figures are looked at, we know that the achievement of reducing rough sleeping, led by the homelessness voluntary sector with the support of Government, is considerable. New York has a rough sleeping population over ten times greater than London's."

Campaigning group St Mungo's insisted street counts were always intended to be a "simple snapshot" of the problem.

Chief Executive Charles Fraser said: "Ending rough sleeping is not about obsessing over numbers, nor is it simply about providing housing for those on the streets.

"We need integrated housing, health and employment solutions. A strong commitment to rough sleepers across all departments both in Government and in opposition is essential if we are to create a better future for homeless people."

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