Protective apparel maker Second Chance Body Armor has issued an urgent warning to public safety officers to replace bulletproof vests containing Zylon fibre, as they may not provide the required level of protection.

Second Chance, the US's biggest maker of body armour, says new research shows that vests constructed partially from Zylon may fail to perform and result in serious injury or death.

The safety notices urge all officers who own and wear Tri-Flex vests or Ultima and Ultimax vests with Performance Pacs to replace these vests immediately with products that do not contain Zylon.

The notices will affect approximately 58,000 Tri-Flex vests and an additional 40,000 Ultima and Ultimax vests with Performance Pacs.

"While Second Chance has not received any reports of field failures of the products in question, we felt it was our obligation to report these new research findings immediately," said Matt Davis, vice president of sales and marketing.

Davis added that Second Chance, which is currently going through bankruptcy reorganisation due to numerous lawsuits filed against it over the performance of its vests, is "aggressively pursuing litigation against the fibre's manufacturer, Toyobo Co Ltd, in an effort to recover funds that can be used to provide a remedy to affected police departments and safety officers."

Second Chance introduced its first products using Zylon in 1998, but later withdrew vests made entirely of the fibre after ongoing testing showed degradation problems that potentially shortened the wearable life of the vest.