Census director Glen Watson said: "I can reassure the public that their census records are secure. We have strict measures in place protecting the nation's census information."
The claim that hackers Lulz Security (LulzSec) broke into the UK census 2011 database looks like a hoax, Glen Watson said. He added that his investigation concluded there was no sign of suspicious activity.
Watson noted LulzSec also denied any involvement, but added: "We are not complacent and will remain vigilant. The security and confidentiality of census data remain our top priority."
The Office for National Statistics launched an investigation earlier this week into claims that information about tens of millions of UK citizens had been stolen by the group as part of an anti-government campaign LulzSec previously announced with associated hacker group Anonymous.
Claims that UK census data had been hacked by LulzSec emerged on the same day that Essex teen hacker Ryan Cleary was arrested in connection with cyber attacks claimed to have been carried out by hacker group LulzSec.
Suspected hacker, 19 year-old Ryan Cleary, faces five charges under the Computer Misuse Act 1990 in connection with three cyber attacks on targets based in the UK.
Police are investigating Cleary's alleged connections to other attacks by LulzSec, believed to have targeted websites including the CIA, the US Senate and Sony.
Police are searching through Cleary's computers that were seized at the time of his arrest. He is due to appear at the City of Westminster magistrates court on Thursday morning.
This story was first published by Computer Weekly