An MP who was just yards from the scene of a terror attack on the Palace of Westminster has warned that security will have to tighten in response.

SNP MP Chris Law was part of a group of MPs who were on their way to the Commons chamber to vote when the alarm was sounded.

The MPs had been "thirty seconds" from the area where the incident happened when they were diverted, he said.

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They had already been on "high-alert" because of the anniversary of the terror attacks in Brussels.

But the first he knew that anything was wrong was when as he prepared to descend an escalator he heard shouts "that 'there have been shootings' plural. I did not know where."

He and a small number of other MPs were evacuated from the building.

He said: The difficulty is that it is such a large estate that no matter how you prepare for these things everybody is in different places at different times.

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I have to say the police were quite swift.

We were moved very quickly downstairs and out the underpass that brought us out onto the (Thames) embankment."

He said that the "biggest fear" the police had was that any of them would get closer to the scene of the attack "which, of course, we were all heading towards because there was a vote in the chamber. We were thirty seconds from being in the very area where the incident happened."

Mr Law said that because of the anniversary "we were on high-alert anyway, looking out for anything out of the ordinary. But nevertheless when anything like this happens it comes as a shock".

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He predicted that Westminster would tighten its security procedures in the wake of the attack.

"You can never over-prepare," he said, "I think after today's incident we will probably have a lot more to do than we have been doing already".