Parliament could be moved out of London in the event of a terror attack, it has been revealed.

A security report from Palace of Westminster serjeant at arms Sir Michael Cummins published on Thursday made clear that MPs and peers would be able to continue their work in an alternative venue if the building was attacked.

Various options have been considered, it emerged in the wake of the recent Commons powder attack on the prime minister.

Sir Michael said there is "no known specific threat to parliament at this time".

But he reminded staff that the general terror threat remains high with the Thameside building considered to be one of the most likely targets.

"The Palace of Westminster is one of the best known buildings in the country," he said.

"Both for this reason and on account of its parliamentary function, it has been high on the list of potential terrorist targets for many years.

"If, for whatever reason, either or both Houses are unable to sit in their chambers, alternative locations are planned and available."

The serjeant at arms is the most senior member of parliamentary staff and holds responsibility for security.

But the report reaffirmed that the Metropolitan Police will take command in "any emergency situation".

It also issued fresh instructions on handling any letters containing contaminated substances.