A man wanted for questioning about a parcel bomb attack on a Dundee couple may have posted more packages to other targets before fleeing Britain, police said last night.

After carrying out extensive checks on passenger flight lists, police now say Iranian-born physicist Cyrus Ghiassy has left the UK.

His hire car was found abandoned three days ago at London's Heathrow airport, although it was believed then that he was still in the south of England, where he had been living.

Police said last night: ''Further inquiries indicate that Ghiassy has left the country. At this time, investigating officers cannot discount the possibility that further packages, which may contain explosive devices, are in existence, possibly having been despatched prior to Ghiassy's departure from the UK.

''Whilst police have no information to suggest a specific threat, in view of the previous incident, anyone who has knowledge of Ghiassy is asked to contact Norfolk Constabulary.''

Earlier yesterday, a Scottish sheriff was warned he could be the next target of the parcel bomber.

Detectives advised Sheriff Richard Davidson to take extra security measures as police stepped up the hunt for 57-year-old Ghiassy, who holds British citizenship and for who's arrest on a charge of attempted murder a warrant has been issued.

Mr Davidson presided over a civil case in 1995, in which Ghiassy was sued for #18,000 in unpaid legal fees by his former solicitors, the Dundee firm of Lawson, Coull & Duncan. Ghiassy lost and was bankrupted.

Former police officer Mike Coyne, a forensic handwriting expert who was injured in a parcel bomb blast at his home in Dundee last week, testified in the court case on behalf of the legal firm that receipts produced by Ghiassy purporting to have been written by senior partner Derek Lawson were forgeries.

Mr Coyne, 63, is recovering in hospital from serious injuries he suffered when the parcel bomb exploded.

His wife Margaret, 60, who suffered neck and abdominal injuries, was discharged from hospital on Saturday.

Two devices identical to the one which injured the couple were intercepted and defused by bomb disposal experts at a freight depot in Thetford, Norfolk.

One of them was addressed to the invalid wife of Mr Lawson at their St Andrews home. The other is understood to have been addressed to retired Home Office handwriting expert Michael Ansell, in Kent.