Anti-terrorist police armed with machine guns are patrolling railway stations because of fears of Madrid-style train bombs.

Stations in Hertfordshire were targeted by police last week and Elstree and Borehamwood and Radlett stations are likely to be next.

Although police say there is no specific threat, some of the county's major rail routes into central London, Gatwick and Luton Airports are of the kind that could become terrorist targets.

Armed Hertfordshire police units are carrying out high visibility operations, including random passenger searches, such as those on Thursday at Welwyn Garden City, Hatfield and St Albans train stations.

Officers, who were instructed to smile, questioned commuters and provided information about anti-terrorist efforts as part of an ongoing campaign.

Flyers were also handed out encouraging people to report any suspicious activity.

"Everyone was happy to co-operate once we explained why we were there," said a police spokesperson, adding: "They said it reassured them."

Chief Inspector Richard Harbon said: "Hertfordshire provides some major transport links and high visibility patrols and checks are part of the reassurance and extra vigilance message we want to put out to the public.

"These patrols are carried out on a regular basis and play an important role in the constabulary's objective to keep Hertfordshire safe."

To report any suspicious activity contact the anti-terrorist hotline on 0800 789 321.

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