London: Police have arrested a man over fears he was planning to carry out a fresh terrorist attack, in a development that will put more pressure on MPs to rewrite the United Kingdom's controversial parole laws.

The arrest of the 34-year-old from Stoke-on-Trent, in central England, is significant because his possible plot was only discovered following a snap review of parole conditions triggered by Friday's attack near London Bridge.

Usman Khan killed two people and injured three others at a prisoner rehabilitation conference before being shot dead by police. The 28-year-old served only half his 16-year prison sentence for plotting to blow up the London Stock Exchange and was automatically released a year ago without any involvement by the UK Parole Board.

His release has triggered outrage in the UK in the final fortnight of the general election campaign and Prime Minister Boris Johnson has moved swiftly to pledge new laws to force judges to hand convicted terrorists a 14-year mandatory minimum sentence.