DETECTIVES are investigating a series of hoax threats that bombs would be detonated on September 11 at North-East livestock markets.

The letters, sent out to coincide with the second anniversary of the attacks in the US, targeted Hexham, Wooler and Scots Gap, in Northumberland.

The hoaxers also claimed the Scottish marts of Kelso and Newtown St Boswells, near Melrose, in Lothian, were to be targeted.

Detectives are investigating whether animal rights campaigners were behind the letters.

One letter was sent to Berwick, Northumberland, where, earlier this month, animal activists protested against the export of 1,800 live sheep to Holland.

Northumbria Police refused to comment, but a spokeswoman for Lothian and Borders police said: "We had a couple of hoax letters saying there were bombs in Kelso's Springwood showground and the auction mart at Newtown St Boswells, near Melrose, on Thursday.

"Our inquiries are ongoing and we don't know if it is linked to any animal rights groups."

A spokesman for campaign group Advocates for Animals hit out at the bomb threats.

He said: "We condemn violence against people just as much as we condemn violence against animals.

"Action like this is very counter-productive to our peaceful campaigns and we would urge anyone doing such things to refrain from such activities.

"However, for animal rights activists to threaten to bomb a livestock mart just does not seem to add up.

"It could well be someone else who has a grudge against these marts for a different reason."