Mail-Well has reacted to the anthrax scare sweeping the US by beginning production of a range of new "safety-oriented" envelopes.

Its Contamination Alert envelope changes colour if it has a biological contaminant inside or has come into contact with a contaminant.

The firm has also introduced an anti-bacterial envelope, which can be treated with agents that can kill biological contaminants.

Its Safety Window envelope is designed for visual detection of unusual substances and has an extra window to show whether any foreign objects have been placed inside.

Mail-Well chairman, president and chief executive Paul Reilly said: "The US mail is still safe today."

The firm said it had received "unprecedented" interest from customers in the past few weeks asking what it could do to minimise risks.