The agency responsible for tracing absent parents is to be given access to phone and email records for the first time, under Home Office rules.
The Child Maintenance and Enforcement Commission (CMEC), which has taken over the heavily criticised
Child Support Agency, said the surveillance powers will allow it to find a hard core of 5,000 missing parents who are refusing to pay towards their children.
The move came as the Home Office announced plans to stop local authorities from using
covert spying techniques for particularly trivial offences such as dog fouling or putting a bin out on the wrong day.
It is part of a review of the use of powers by public bodies under the Regulation of Investigatory Powers Act (Ripa), which has
town halls have been accused of abusing.
Investigators for the CMEC will now be given access to communications data stored by phone companies and internet service providers in cases where other methods of investigation have failed.
data shows who the target is speaking to on the phone, or contacting by emai. It will allow access to billing data showing an absent parent's address.
As well as tracking down those who have escaped detection, the powers will also be used on
parents who do make some payments but are suspected of lying about their wealth.
Chris Huhne, the Liberal Democrat home affairs spokesman, said: Only this Government could claim to be curtailing Ripa powers while extending them to a new body
for the investigation of a different offence. Ministers cannot be trusted to govern the use of these intrusive powers, which is why their use should be authorised by magistrates.
Dylan Sharpe, campaign director of Big Brother Watch, said: Saying that these new extensions to RIPA will only target benefits cheats and parents that fail to pay child support is all well and good; but given recent experience most people will be waiting for cases that show the powers are being used for other, more nefarious reasons.
Ministers rejected suggestions that magistrates should authorise all uses of Ripa, arguing it could seriously impair investigations.