Ken Livingstone's guru on radical Islamic politics has been exposed as an undercover police officer who infiltrated the animal rights movement in the 1980s.

Until August, Dr Robert Lambert was the co-director of the European Muslim Research Centre (EMRC) at Exeter University.

He advocates a controversial policy of working closely with non-violent Muslim radicals. In his former role as head of the Muslim Contact Unit at the Metropolitan Police, he was closely associated with Ken Livingstone's 2005 decision to welcome the Egyptian cleric Yusuf al-Qaradawi to London.

Sheikh Qaradawi is a major figure within the Islamist Muslim Brotherhood and a supporter of suicide bombing against Israel. He does not view "martyrdom operations" as terrorism.

Dr Lambert was exposed as an undercover officer by the Guardian this month. Using the alias Bob Robinson, he infiltrated the Animal Liberation Front and Greenpeace, and even tricked a woman into having a relationship with him to provide a cover story. He has since issued an apology for deceiving his former lover. Dr Lambert ended up heading up the undercover unit but eventually left to return to more regular duties.

Ironically, Dr Lambert is a regular contributor to the Guardian as an expert on policing the Muslim community. After being exposed, questions were asked about the nature of his work within the UK Muslim community. In his latest piece for the newspaper he wrote: " I did not recruit one Muslim Londoner as an informant, nor did I spy on them. They were partners of police and many acted bravely in support of public safety."

In March, Exeter University was forced to issue a statement about funding which the EMRC had received from the Cordoba Foundation and Islam Expo, saying that it was not aware of any relationship between the two organisations and the Muslim Brotherhood. The statement followed questions from Harlow MP Robert Halfon.

In his memoir, Mr Livingstone repeatedly defends the invitation to Sheikh Qaradawi, citing Dr Lambert's advice in his defence, and quoting his praise for his [Mr Livingstone's] work with minority Muslim groups.

The former mayor also recalls an internal Special Branch report on Sheikh Qaradawi which claimed the Egyptian's "support for Palestinian suicide bombers adds credibility to his condemnation for al-Qaeda". Mr Livingstone said he felt such engagement could help broker dialogue and repeated his belief that after his election in 2000, racist and antisemitic incidents in the capital had declined each year.

But a CST spokesman said: "It may sound like realpolitik to say that Sheikh Qaradawi could save the lives of Londoners by promoting the murder of Israelis, but it is deeply immoral and totally wrong: you either support terrorism or you condemn it."