The Sun has lost 1,280,000 readers a week falling to 7,940,000, while the Daily Mirror is down 766,000 to 4,234,000, according to the report.
This is despite the tabloids recording a marginal increase in circulation in the latest set of Audit Bureau of Circulation results.
The National Readership Survey figures measure the estimated readers of a publication as opposed to the number who buy a paper or magazine, as recorded in the ABCs.
While the majority of papers suffered a loss in readers according to the NRS, the tabloids were hit the worst in the survey.
The Daily Star lost 11% to reach 1,820,000 and The Daily Record was down 12% to 1,260,000.
The Guardian's estimated readership shot up by a whopping 21% to reach 1,238,000 readers, compared with 1,0245,000 the year before.
The news will give the Guardian Media Group further reason to celebrate as its new Berliner format launched last week to a mainly positive response with sales rising by as much as 40% on its first day.
The Times was the only other weekly paper to prosper, with the NRS recording a 10% hike in estimated readers from 165,500,000 a week in 2004 to 182,100,000 between January and June 2005.
The Sunday papers fared better than the weeklies in the survey. The Guardian Newspapers-owned The Observer added 24% or 248,000 readers to reach 1,282,0000 -- the highest climb of any paper in the survey. The Independent on Sunday recorded a 15% boost to 777,000 estimated readers overall.
The Sunday Times also performed well, adding 11%, while the Mail on Sunday and Sunday Mirror added 3%.
The worst performance came from The People, which lost 19% of its estimated readers.
Like its sister title The Sun, the News of The World lost 14% of its estimated readers. The weekly scandal-led tabloid lost 1,389,000 of its estimated readers to reach 8,536,000.
The Sunday Mirror and The Sunday Mail and were down 9% and 10% respectively.
The NRS is a continuous survey based on interviews with 36,000 UK adults annually.
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