The Home Office is suing the company for the £300,000 that it says it had to spend to change every lock at Feltham Young Offenders' Institution in London following ITN's report.
ITN broadcast close-up images of a key which security experts said could be used by some expert locksmiths to create copies of the keys. ITN's report was about the racially motivated murder of 19-year-old Zahid Mubarek.
Broadcasters usually sign a contract in order to film inside prisons which contains an agreement not to show footage of keys or locks because its broadcast is a security hazard.
Prison authorities have claimed that it cost £298,595 to change 11,000 locks and 3,200 keys and the Home Office is suing ITN for that amount, which it says the company, and not the tax payer, should pay.
"We can confirm the Home Office has taken out legal proceedings against ITN to recover costs for the relock at Feltham Young Offenders' Institution in June 2006," a Home Office statement said.
ITN is said to have offered to pay the Home Office £10,000 when first contacted about the gaffe, but the legal action shows that the Government wants ITN to pay in full for the mistake.
