ARMED police officers have been seen this morning patrolling two Sussex railway stations.

An officer with a machine gun was stationed at Brighton Railway Station at 8am.

While two colleagues were seen talking to passengers at Lewes Railway Station at the same time.

The appearance of armed officers comes in the wake of a decision to raise the threat level from "severe" to the highest "critical" setting by experts at the Joint Terrorism Analysis Centre (JTAC).

A Sussex Police spokeswoman said the force was continuing to keep all policing under review and in light of the increased threat level have increased our armed policing (ARV) capability by increasing our current armed officers' shifts to 12 hours. 

She added that they had also enhanced high visibility policing. 

The Royal Sussex County Hospital is also implementing increased security measures.

A spokeswoman for the hospital said: "Following the national security alert being raised to critical all health organisations have been instructed to work to resilience plans."

She said it meant that extra security staff would be on duty and patrolling the hospital and there will be more ID checks.

Armed troops will be deployed to guard "key locations" such as Buckingham Palace, Downing Street, the Palace of Westminster and embassies, Scotland Yard said.

Soldiers will replace armed police at many sites under Operation Temperer, which is being enacted after security experts warned the Government that another terrorist attack could be imminent.

The decision taken at a meeting of the Government's emergency Cobra committee will mean soldiers will play a key role in protecting civilians and free up armed police officers to help fight the terror threat.

No troops have been depoloyed in the county as Sussex Police say they are not required at this time. However the forcewill keep the situation under review, a spokeswoman said.