Police in London have received a coded bomb threat from Irish republican dissidents warning of an explosion.
Scotland Yard says the threat is not specific about where or when an attack could take place.
Officers are telling Londoners to be vigilant, but carry on going about their business as usual.
A controlled explosion Is believed to have been carried out on a suitcase.
Security was heightened today after the “non-specific” threat was issued to authorities last night.
Amid increased police activity across London, areas around the Mall were cordoned off for several hours.
A Scotland Yard spokesman said: “A bomb threat warning has been received relating to central London today. The threat is not specific in relation to location or time.”