Britain's MI5 intelligence service formally launched an internal investigation on Monday to review whether it should have paid more attention to warnings about the behavior of Salman Abedi, the suicide bomber who killed 22 people last week in an attack on Ariana Grande's Manchester concert.

"There is a lot of information coming out at the moment about what happened, how this occurred, what people might or might not have known," Home Secretary Amber Rudd told media on Monday. "It is right that MI5 take a look to find out what the facts are. We shouldn't rush to make any conclusions at this stage."

There are reports that prior to the May 22 bombing, two people who knew Abedi made separate calls to a police hotline to warn the authorities against Abedi's extremist views.

The British Broadcasting Corporation (BBC) also said that as a teenager, Abedi had been involved in the armed insurgency against former Libyan dictator Moammar Gadhafi during his school holidays. Gadhafi was killed by Libyan rebels in October 2011.

A "post incident investigation" will examine how the Manchester bomber was overlooked. A separate report was being prepared for ministers and those who oversee MI5's work, according to the BBC.

"This is a review that would seek to answer whether there are lessons to be learned from how the security service handled the intelligence on Abedi," the Reuters news agency cited a source as saying.

Fresh arrest

A 23-year-old man was arrested in Shoreham-by-Sea, some 400 kilometers (250 miles) from Manchester, "on suspicion on offences contrary to the terrorism act," Greater Manchester Police said on Twitter Monday morning.

Police also raided a building in a southern Manchester suburb and another in the city of Chester in connection with last week's attack.

Read more: In Manchester, a show of determination, anger, fear and love

British authorities believe Abedi was part of a network, with the interior minister, Amber Rudd, saying Sunday there were "potentially" still members of the cell at large.

The Monday arrest has brought the total number of people arrested in connection with the Manchester bombing to 16. Two were released by police without charge, while 14 remain in custody.

Threat level down a notch

On Saturday, Prime Minister Theresa May said developments in the investigation prompted intelligence experts to lower the threat level in the country from "critical" - the highest available - to "severe," claiming that a critical part of the network had been dismantled.

Still, security remains high at large-scale public events, including the Great Manchester Run, where some 40,000 runners took to the city streets.

Read more: Manchester's music scene after the terror attack

Media reports say that people who knew Abedi had raised concerns about him and his views as far back as 2012.

"The intelligence services are still collecting information about him, but I wouldn't rush to conclusions, as you seem to be, that they have somehow missed something," Home Secretary Rudd said.

When asked how many potential militants the government was concerned about, Rudd said Britain's security services were tracking 500 different potential plots, involving 3,000 people as a "top list," with an additional 20,000 beneath that.

 

shs/msh (AFP, Reuters)