London attacker not linked to IS or al-Qaida

LONDON -- A senior British counterterrorism officer said police have found "no evidence" Westminster attacker Khalid Masood was associated with the Islamic State group or al-Qaida.

Deputy assistant commissioner Neil Basu said Masood clearly had "an interest in jihad," but police have no evidence he discussed his attack with others.

Basu said in a statement the attack in which Masood used an SUV and knives to kill four people in London "appears to be based on low sophistication, low-tech, low-cost techniques copied from other attacks."

He said Masood was not a "subject of interest" for counterterror police or the intelligence services before last week's attack.

British police said two people remain in custody after last week's attack in London as messaging services face criticism for encrypted networks that allow attackers to communicate in secret.

Masood is believed to have used the messaging service WhatsApp before running down pedestrians on Westminster Bridge and storming a gate outside Parliament, armed with two knives.

Encryption makes it more difficult to know whether Masood was acting with an accomplice. Britain's Home Secretary, Amber Rudd, wants technology companies to do more to make it possible for security services to have access to such messages.

Police said a 30-year-old man arrested in Birmingham on Sunday and a 58-year-old man arrested shortly after the attack remain in police custody.