ARMED troops will be sent to guard “key locations” after the terror threat level was raised to “critical” in the wake of the Manchester attack.

Soldiers will replace armed police at Buckingham Palace, Downing Street, the Palace of Westminster and embassies to free up police to protect citizens.

Security experts have warned that another terrorist attack could be imminent.

Commander Jane Connors, leading the London policing operation, said: “We will do all we can to protect the capital that we serve at this unsettling time.”

The plans mean there could be soldiers supporting police at big events, including the FA cup final at Wembley on Saturday or the Champions League final in Cardiff on June 3.

While there is no evidence that links an attack to the county, Essex Police have stepped up patrols and armed officers will guard major buildings.

BJ Harrington, deputy chief constable for Essex Police, said: “From today and until further notice people in Essex will see an increased police presence in the county and that includes armed police officers.

“It is unlikely you will see military personnel patrolling in Essex, but if you do it does not mean that there is a specific threat near you.”

Four people have been arrested so far in connection with the attack, which killed 22 people and injured dozens of others.