Detectives are investigating a possible phone call made by the main suspect in the knife killing of a British MP just minutes after the attack.
Police believe Mr Ali, 25, was acting alone but are trying to find out if he made a call or text to anyone else with knowledge of the attack, according to media reports.
He continues to be questioned by police following his arrest minutes after the attack. He can be held until Friday before he has to be charged or released.
It has emerged that Mr Ali received support from the government’s counter-terrorism programme following a report from an educational centre in London.
He was referred to the Prevent early intervention scheme in 2014 and later voluntarily joined the mentoring and de-radicalisation programme Channel, according to The Guardian newspaper.
He was said to be among a group who were of concern to the authorities and spent months in the programme before he left. Mr Ali’s father is said by friends and former colleagues to have been an outspoken critic of terrorism during his time as a senior official in the Somalian government.
Critics of the Prevent scheme said there was little monitoring of individuals after they left the programme and it is unclear what role authorities had in Mr Ali’s life in the seven years before the attack. He was never a formal subject of interest to MI5.
The programme is currently under review and that will now be fast-tracked. The review has been hampered by problems, including a dispute over who would lead the assessment.
The first lead reviewer left following criticisms he had previously expressed strong support for the programme. He was replaced by former charity watchdog head William Shawcross.