A three-minute silence has been held across the UK and European Union for those killed by the Madrid train bombs.
People in London stopped at 1100 GMT for the silence
Irish Prime Minister Bertie Ahern, whose country holds the EU presidency, proposed the silence.
BBC One and several BBC radio stations were silent at 1100 GMT to honour the 200 who died and 1,400 injured in Thursday's attacks.
One woman originally from Northern Ireland and another Briton living in Spain were also injured.
BBC Radio 1 and Radio 2 held one minute's silence, while Radio 4, Radio Five Live and the Asian Network held three minutes' silence.
ITV1 observed the silence as part of its national news broadcast, but Channel 4 did not join in.
The moment was marked at London's Heathrow and Gatwick airports as well as railway stations across the country.
'Still in shock'
Mr Ahern said the silence would "demonstrate our collective sense of solidarity with Spain and its people and our steadfast determination to fight the scourge of terrorism which threatens all of our basic freedoms".
More than 50 people from the Spanish Embassy in London stood on the steps of their building just before 1100 GMT.
Spanish ambassador Marques de Tamaron joined his staff and Spanish residents in London, heads bowed and hands clasped as the three minutes passed.
Maria Jose Anvarro, who works in the embassy's administrative department,
said: "The mood in our offices is still very sad. We all feel very upset and
we're all still in shock."
Jose Capas, who has lived in the UK for 15 years, said many of his countrymen
have still not come to terms with what happened.
He said: "We are sad and depressed - so many innocent people have lost their
The silence was also observed by about a dozen staff from the
Norwegian Embassy, whose offices overlook the Spanish Embassy.
In Europe, Ireland, France, Italy, Germany and Belgium also took part, as well as the non-EU Czech Republic, Bulgaria and Croatia.
Bulgaria lost four of its nationals in the attack and Poland two.
The UK Government's decision to join the silence follows the playing of the Spanish national anthem during the Changing of the Guard ceremony at Buckingham Palace on Sunday.
The "Marcha Real" was played during the ceremony, attended by the Spanish ambassador, the Marquis of Tamaron, and watched by several hundred people outside the palace gates.
On Friday a Spanish Mass was held at Westminster Cathedral in London.
The same day Deputy Prime Minister John Prescott attended Madrid's official anti-terrorism rally and offered the UK's solidarity to Spain.