Britain on high alert as military personnel deployed around the country

Three men were arrested in Manchester on Wednesday as soldiers took to the streets in the wake of the Manchester bombing which left 22 people dead.

Police officers stand on duty at the cordon surrounding the Manchester Arena in Manchester, Britain, May 23, 2017.  [Photo/Agencies]

Soldiers were also seen backing up police as they raided a property in central Manchester.

There was added tension in the UK as officials said they believed that Salman Abedi, 22, the bomber, must have acted with others who could possibly strike again.

Four more men have been arrested in Manchester in connection with a suicide attack at an Ariana Grande concert on Monday which left 22 people dead and 59 injured.

UK home secretary Amber Rudd said the bomber, Abedi, was known to the security services "up to a point" adding he was likely to have been working with others.

Prime Minister Theresa May raised the terror threat level to critical – the highest possible rating meaning another further terrorist attack on UK soil is feared to be "imminent".

The decision means military personnel can be deployed on the streets to support the police in protecting key areas, such as Buckingham Palace, Downing Street, embassies and the House of Parliament.

Rudd said that Monday's attack was "more sophisticated than some of the attacks we've seen before and it seems likely – possible – that he wasn't doing this on his own".

The government said around 980 members of the Armed Forces will be deployed by the British army around the UK to support police in the aftermath of the Manchester attack.

This means by replacing armed police on guard duty, officers are freed up to focus on arrests and other duties.

The soldiers will be in uniform but will be working under the command of the police.

Rudd also stressed that the move was an "absolutely temporary" response to the immediate threat.

A military presence may also be felt at major sports or entertainment events such as the FA Cup final at Wembley this weekend or the Champions League final in Cardiff next week.

This is only the third time that the threat level was raised to critical. In the previous occasions, the risk was lowered after a few days.

Meanwhile, officers have raided a block of flats close to Manchester Piccadilly Station.

Residents described how armed police and men clad in balaclavas stormed the Granby House building on Granby Row, in the city center.

Greater Manchester Police said: "Officers have this afternoon carried out a search at an address in Manchester city center as part of the investigation into the horrific incident at Manchester Arena. That search is ongoing."

To contact reporter: boleung@mail.chinadailyuk.com