Concrete blocks have been placed around Britain's parliament as police step up security measures in London.
The large blocks were placed strategically around Westminster and other government buildings in central London in a bid to prevent vehicles with explosives being driven inside and set off.
"These measures are being carried out on a precautionary basis in light of events around the world and the fact that security in the capital remains at a high level," London's Metropolitan Police Service said.
"There is no specific intelligence of places, events or people in the UK that would lead us at the moment to issue specific warnings to the public," the statement added.
Suicide bombers killed 34 people - mostly foreigners - in attacks on expatriate compounds in the Saudi capital Riyadh, and another 41 people, mainly locals in a series of co-ordinated explosions in Casablanca, Morocco.