The Westminster attacker was born as Adrian Russell Ajao in Kent, police investigating the atrocity have said as confusion remains over Khalid Masood’s numerous aliases.

Scotland Yard’s Deputy Commissioner, Mark Rowley, identified the suspected Isis supporter only as Adrian Russell in a press conference but the Metropolitan Police later gave his surname as Ajao.

His birth name was originally reported as Adrian Elms, with his mother named as Janet Elms. The Daily Mail reported that she married a man named Phillip Ajao in West Sussex when Masood was a small child.

It remains unclear precisely when Masood’s various surnames were changed and he also went under aliases including Khalid Choudry. The Home Office is understood to be investigating the issue.

Deputy Commissioner Rowley said officers were investigating whether Masood was radicalised by online jihadi propaganda or if he may have been directed by terrorists.

“Our investigation focuses on understanding his motivation, his preparation and his associates,” he added.

“Our determination is to find out whether he acted totally alone inspired by terrorist propaganda or if other have encouraged, supported or directed him.”

Detectives are “looking at his history” amid reports Masood may have travelled overseas.

Two more “significant” arrests were made in the West Midlands and North West overnight, with nine people currently in custody in relation to the attack, with five searches ongoing and 16 completed.

One woman has been released on bail as detectives sift through 2,700 seized items and masses of computer data, as well as interviews with 3,500 witnesses and video footage taken by members of the public.

Deputy Commissioner Rowley said hundreds of officers were involved in the counter-terror probe codenamed Operation Pacific across the UK.

He appealed to the public for information on Masood, particularly from anyone who could provide information on his associates and recent travel.

“There might be people out there who did have concerns about Masood but didn’t feel comfortable, for whatever reason, passing that information to us,” he added.

His attack left four victims dead and 50 others injured of 12 different nationalities, with 31 requiring hospital treatment.