A retired couple found themselves at the centre of a chemical bomb scare as they opened their post.

Inside one envelope they found a white power and the chilling message: "Breathe this and die".

The terrified couple immediately telephoned police who told them: "Get out of the house now."

Police and fire crews with chemical hazard gear raced to the semi-detached home in Heath Hill Avenue, Lower Bevendean, Brighton, just after 10am yesterday.

Terry Pay's house is close to one of two Brighton homes raided by police at the weekend in connection with the failed suicide bomb attacks in London.

The 60-year-old retired roofer thought the letter "bomb" was somehow connected. He said: "It was very frightening."

Police were the first to examine the envelope and they quickly established the power was harmless.

Sue Heard, spokeswoman for Brighton and Hove police, said: "The substance turned out to be cornflour but this must have been extremely worrying for the couple.

"We are treating the incident very seriously."

Ms Heard said the words on the envelope were sinister and she said forensic experts were examining the envelope for fingerprints and clues to the identity of the culprit.

Mr Pay, who has four children and grandchildren, said: "This was very upsetting and terrifying. Everyone is on edge at the moment."

His wife Carol, 57, said: "It was so frightening seeing all the policemen in their riot gear, ambulances and fire engines turning up outside our home. I didn't think it was anything serious at first until I saw the words breathe this and die'. I was so shocked."

Police appealed for anyone with information to contact PC Andy Snadden at Brighton police on 0845 6070999.