Shadow home secretary David Davis plans to fight a parliamentary by-election in which he will campaign against the creation of "a database state."

The Tory MP is a vocal opponent of the drive to set up a national ID card system and plans to resign his seat to force the election in which he will stand.

Davies is credited with persuading the shadow cabinet to commit to scrapping identity cards. Davis announced his maverick decision – taken without Tory leader David Cameron's support – on the steps of the public entrance to the Commons.

He said: "We will have shortly the most intrusive identity card system in the world, a CCTV camera for every 14 citizens, a DNA database bigger than any dictatorship has, with thousands of innocent children and millions of innocent citizens on it."

He said he opposed the "creation of a database state opening up our private lives to the prying eyes of official snoopers and exposing our personal data to careless civil servants and criminal hackers".

Davis plans to fight the single issue by-election amid the suspicion he was close to clashing with Cameron, over an attempt to bounce the shadow cabinet into committing the Tories to repeal the provision giving the police power to detain suspects for up to 42 days.