She said: "I am so deeply shocked, saddened and numbed by the actions my son has taken that have killed and injured innocent people in Westminster.

"Since discovering that it was my son that was responsible, I have shed many tears for the people caught up in this horrendous incident.

"I wish to make it absolutely clear, so there can be no doubt, I do not condone his actions nor support the beliefs he held that led to him committing this atrocity.

"I wish to thank my friends, family and community from the bottom of my heart for the love and support given to us."

Scotland Yard said that, while it had not found evidence linking Masood to the group, he "clearly" had an interest in jihad.

Deputy Assistant Commissioner Neil Basu, the senior national co-ordinator for UK counter-terrorism policing, said: "His attack method appears to be based on low sophistication, low-tech, low-cost techniques copied from other attacks and echoes the rhetoric of IS leaders in terms of methodology and attacking police and civilians, but at this stage I have no evidence he discussed this with others.