A leading community representative has told Sky News that people are increasingly being radicalised in the UK's prisons - and the Government must do more to stop it.
Intelligence officials are examining whether Westminster attacker Khalid Masood, who had converted to Islam, was groomed in jail.
Research from the Henry Jackson Society suggests Muslim converts are four times more likely to commit terror offences than those born into the faith.
A Muslim association has warned it has received reports of attempts to recruit criminals behind bars for acts of violence on British streets.
Rafiq Hayat, president of the Ahmadiyya Muslim Association, told Sky News: "It is worrying and this is something the Government should take seriously and find ways to not allow that to happen in our prisons in the UK."
Anti-radicalisation campaigners have warned an act of terror by a man in his 50s is worrying, and say promoting awareness should not be exclusively aimed at younger generations.
Nicola Benyahia started a counselling service for families affected by radicalisation after her 19-year-old son Rasheed was killed fighting for Islamic State in Syria.
When asked about Masood, who was 52, she said: "Generally speaking, when they are older, they tend to possibly have the ideology but they don't have the means - maybe because of commitments with family and children.
"So what they tend to do is become recruiters themselves. For somebody to carry out an atrocity as we saw on Wednesday is fairly unusual."
Ms Benyahia said everybody has a duty to understand and prevent the threat of radicalisation - not just educators in schools, colleges and universities.
After the 7/7 London bombings of 2005, the UK was forced to examine why attackers would want to bring terror to the streets of a country where they were born.
One of the suicide bombers who targeted the Underground, Germaine Lindsay, was a convert.
The two British-born men who killed Fusilier Lee Rigby in 2013, Michael Adebolajo and Michael Adebowale, had converted from Christianity.
Jahan Mahmood, a former government adviser on radicalisation, has said there are similarities between the Westminster attacker and one of the men convicted of murdering Lee Rigby - as both were converts, both are believed to have spent time in prison, and both staged knife attacks.
He added: "At this moment, we have no conclusive picture of (Masood's) radicalisation so to speak - was it in prison, was it after prison, was it because of people that he may have known from prison."
Mr Mahmood warned it is "pretty undeniable" that there is an issue in prisons that needs to be dealt with.