Animal rights extremists have renewed their campaign of hate against cat breeder Chris Brown and Oxford professor Colin Blakemore after letter bombs were posted to their homes.

Two more devices were posted to two workers at Mr Brown's farm in Hillgrove, Minster Lovell, near Witney. Police, who described the incidents as "cowardly attacks", say all four victims escaped unhurt after realising the packages were suspicious.

The Army was brought in to deal with the packages.

Assistant Chief Constable Robert Davies said: "These letters had got the potential to cause serious injury to the recipient and it is important that members of the public are vigilant and do not hesitate to contact the police if they receive any suspicious packages.

"These letters are a cowardly attack and an unacceptable form of protest." Earlier this year a group calling themselves the Provisional Animal Liberation Front sent Mr Brown a bomb threat.

Campaigners have also staged demonstrations outside his farm over the last 12 months.

Professor Blakemore, head of physiology at Oxford University, has been a regular target for extremists since 1987 after allegations about experiments on kittens as part of his work into the condition lazy eye.

He has had to turn his home into a fortress after repeated attacks.

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