POLICE have opened an investigation following allegations that former University of St Andrews lecturer Bob Lambert who infiltrated animal rights campaigners when an undercover officer set fire to a high street department store.

Scotland Yard has said it will reinvestigate a 1987 bomb attack by animal rights activists on a department store after new information was found by a probe into undercover officers including Mr Lambert.

The force said it is "pursuing a number of lines of inquiry" including advances in DNA techniques and evidence that has been uncovered as part of Operation Herne, the investigation into the Met's secretive Special Demonstration Squad.

It is set to reinvestigate the planting of an incendiary device at Debenhams in Harrow nearly three decades ago.

The launch of the investigation comes after Green MP Caroline Lucas aired allegations in parliament that Mr Lambert, a Met undercover officer who pretended to be a radical protester for five years, had planted the device.

Mr Lambert helped secure the convictions of two figures linked to the Animal Liberation Front responsible for firebombing branches of Debenhams.

He had infiltrated the ALF, which was behind that attack and two others at branches in Romford and Luton.

In 2012, MP Caroline Lucas used parliamentary privilege to name Mr Lambert as the police mole who had planted the Harrow device. He denied any role in the bombing.

In December, Mr Lambert, left the University of St Andrews and a London university amid an outcry about his past.

Mr Lambert, who worked for the Metropolitan Police's Special Demonstration Squad (SDS) in the 1980s and was paid to infiltrate animal rights and environmental groups, had been able to continue us career as a lecturer in terrorism and political violence at the university despite the Debenhams allegations.

Andrew Clarke and Geoff Sheppard, who were jailed for planting devices at the Romford and Luton stores, launched appeals against their convictions in 2014 on the grounds that an undercover officer had been involved in the case.

Scotland Yard said: "A team is now pursuing a number of lines of inquiry which were identified following a thematic review of the original investigation, by the then Bomb Squad.

"This will include exploiting potential advances in DNA techniques, new information that has been established by Operation Herne and claims made under parliamentary privilege by an MP in 2012."

The Met said that they are not identifying anyone who is the subject of the investigation, which is being led by a senior officer in its professional standards directorate.

Mr Lambert has admitted having sexual relationships with activists and fathering a child with one woman, but denies the Debenhams claims.

He previously said: “It was necessary to create the false impression that I was a committed animal rights extremist to gain intelligence so as to disrupt serious criminal conspiracies. However, I did not commit serious crime such as planting an incendiary device at the (Debenhams) Harrow store.”

Lambert said that the aim of the covert work was to “identify and prosecute members of the ALF who were then engaged in widespread incendiary and explosive device campaigns against vivisectors, the meat and fur trades.”