The group accuses the Government of manipulating official figures for the calendar year 2001 to detract from the actual number of communications it was intercepting at the time.
Whilst official reports show the number of interception warrants issued fell from 1,900 in 2000 to 1,445 in 2001, official figures no longer take into account changes to warrants - otherwise known as "modifications" - the group says.
Modifications made to an existing warrant used to result in a new warrant being created, prior to the introduction of the Regulation of Investigatory Powers Act 2000 (RIPA).
By calculating the figures to incorporate moderations to existing warrants, the actual number of warrants issued for 2001 is 3,427, the group says.
Tony Bunyan, Editor of Statewatch, said: "The official figures are a travesty. Figures are provided which show surveillance warrants have doubled since Labour came to power in 1997 - they are now more than double the figures in the Second World War. But no figures are given on other major changes brought in under RIPA 2000 that would show the real extent of interception.
"The new method of issuing warrants and changes to them is said to make life easier for officials but at the same time it hides from public view the true extent of surveillance."
A spokesman for the Home Office defended the figures.
She told Shout99.com doubling up the number of individual surveillance cases by added "modifications" - which can count as a person's mobile number or email address changing - presented an unrealistic version of actual surveillance levels.
She added: "all statistics on surveillance levels are collated by an independent analyst (the Interception of Communications Commissioner) who operates outside of Government and takes modifications into account when preparing data for public record."
According to the Home Office, 464 people were under surveillance on December 2001.
Home Office plans to force Internet Service Providers to retain data on users as part of its surveillance plans drew criticism from the All Party Internet Group, recently. The Group described the plans as: "damaging, potentially unlawful and unhelpful in the fight against crime."
Richard Powell, © Shout99.com 2003