A spectacular prison break by Belgium's most famous escapee has led to new calls for an overhaul of Belgian jails.
Benallal, self-styled "escape king", has to serve over 50 years in jail
Self-styled "jailbreak king" Nordin Benallal is still at large after his accomplices used a helicopter to free him from prison on Sunday.
Previous escapes had seen him run from a prison van, walk out of jail wearing a wig and sunglasses and scale a prison wall with a rope ladder.
Politicians and unions are now calling for more investment in prison security.
Benallal escaped from a prison in Ittre, 30km (20 miles) south of Brussels, after one of his accomplices landed a hijacked helicopter in the prison yard.
Commotion followed the landing, enabling Benallal and his accomplices to take two guards hostage and flee the prison in a car.
The facility was opened in 2002 and is reputed to be one of the most modern and secure in the country.
But a prison staff trade union spokesman, Michel Jacobs, said there was no such thing as zero risk.
Benallal's escape was Belgium's second successful prison break involving a helicopter in 2007.
An escape from another prison on 15 April prompted a report by the Federal Justice Service on enforcing prison security.
Benallal escaped from Ittre, one of Belgium's safest prisons
One proposed measure - already implemented in five prisons - is the placing of wire nets over prison yards, at a cost of 3m euro (£2.09m).
But structural concerns mean this is not possible in all prisons.
Alternative and cheaper methods proposed include the jamming of mobile phone signals and installation of new surveillance cameras.
Meanwhile, prosecutors say recapturing Benallal might prove difficult.
As he already faces more than 50 years in jail, he may resort to desperate measures if cornered, Belgian media report.