Dogs taken from Huntingdon research facility MBR Acres in anti-vivisection protest
Five dogs were taken from an animal research facility during the second break-in by anti-vivisection protesters in two days.
Eleven people - eight women and three men - were arrested on suspicion of criminal damage, aggravated trespass and assaulting an emergency worker following a demonstration at MBR Acres in Cambridgeshire in the early hours of Sunday.
Police have now confirmed a second break-in took place at 3am on Monday, when a further 12 people were arrested on suspicion of burglary.
A spokesman said three dogs were thought to have been stolen however at a High Court hearing a barrister representing MCR Acres told a judge it was five.
The site, in Wyton, near Huntingdon, hit the headlines in November last year when singer and former Pop Idol Will Young took part in a demonstration outside the facility which breeds Beagles for scientific research.
Experiments are not carried out at the site, but protesters object to the fact that puppies are reared indoors - though MBR insists that the animals are healthy, content and comfortable.
At Monday's High Court hearing, Caroline Bolton, for MBR Acres, told Mr Justice Nicklin that "urgent investigations" were under way following the break-ins.
Ms Bolton described the incidents as "serious" and said police had attended, telling Mr Justice Nicklin that dogs were "taken off the premises".
All protesters arrested on Sunday have been released on bail. Police said none of them were from Cambridgeshire.
Those arrested on Monday remain in custody at Thorpe Wood police station.
MBR Acres has taken High Court action in the wake of previous anti-vivisection protests at the Wyton site, and a judge has made an injunction preventing protesters entering an exclusion zone.
Mr Justice Nicklin was overseeing the latest stage of that ongoing litigation on Monday - and making decisions on a number of legal issues.
Two earlier protesters are awaiting sentence after Mr Justice Nicklin made contempt of court rulings following an earlier hearing.
MBR Acres had accused Michael Maher and Sammi Laidlaw of entering an exclusion zone at the Wyton site in breach of a court order.
Maher and Laidlaw, who are part of a Camp Beagle protest group, initially denied contempt.
But they told Mr Justice Nicklin at a hearing in April that, having seen evidence, they may have breached an injunction but had not meant to.
Mr Justice Nicklin said in a written ruling published in May that Maher and Laidlaw were both guilty of contempt because they had admitted breaching an injunction by entering an exclusion zone.
Maher, who is in his 40s and lives near Dorchester, Dorset, and Laidlaw, who is in her 30s and lives near Southend, Essex, are among a number of protesters against whom MBR has taken legal action.