In a move that could paralyse the movement of cash around the country, the measures sought by the workers include secure parking at banks and ATMs, the installation of CCTV cameras and secure facilities, such as bunker rooms, to open up cash machines.

Siptu, which represents the security workers involved, is relying on a rarely-used clause in the 2005 Safety Health and Welfare at Work Act, which allows workers to refuse to do a job if they believe it poses a "serious and imminent danger" to their health and safety.

The security workers' decision follows a renewed spate of attacks and kidnaps on security workers and their families. The latest occurred last week when a criminal gang got away with Euro500,000 after the family of the assistant manager of the Balbriggan branch of Bank of Ireland was kidnapped while he was forced to go in and withdraw the money.

Last month, a criminal gang got away with Euro1.3m from a Securicor cash van in Carlow after the wife of one of the Securicor workers was kidnapped and held hostage.

The Carlow attack followed a botched kidnapping when two employees of Chubb Ireland managed to get free from their captors in north Dublin and foil what would have been a Euro1.5m heist.

As well as the threat of refusing to carry cash to unsafe locations, Siptu also wants panic alarms to be fitted in the homes of key security staff in a bid to thwart the kidnappers.

The union also wants detailed background checks to be carried out on all prospective employees before they take up employment in the security industry. It was obvious from the Carlow attack that the gangs had detailed inside knowledge of Securicor's operations, including the names and addresses of the targeted employees.

Kevin McMahon of Siptu said at the time that this aspect of the attacks was a major concern for his members, who could never be sure whether a new colleague could turn out to be the person to kidnap his family.

On garda assistance, the workers want to see armed escorts on high-value, high-risk deliveries until the risk of armed attacks and hostage-taking is eliminated.

With regard to the workers' threat to refuse to service unsafe cash locations, Kevin McMahon said the union will notify the CIT companies of locations they consider to be "high risk".

"We will allow a reasonable period for the employers to address security weaknesses. If the management fails to address these issues then our members will not put themselves and their families at risk, " said McMahon.