The internal police report found the million-plus cameras in London rarely help catch criminals.
In one month CCTV helped capture just eight out of 269 suspected robbers.
David Davis MP, the former shadow home secretary, said: "It should provoke a long overdue rethink on where the crime prevention budget is being spent."
He added: "CCTV leads to massive expense and minimum effectiveness.
"It creates a huge intrusion on privacy, yet provides little or no improvement in security. More...