World leaders supporting London over 'tragic ordeal'
World leaders have condemned the terror attack outside the Houses of Parliament that ended in the deaths of four people.
US President Donald Trump was quick to offer his support, tweeting: "Spoke to UK Prime Minister Theresa May today to offer condolences on the terrorist attack in London. She is strong and doing very well."
White House spokesman Sean Spicer said London and the UK government have the "full support" of the US.
In France the lights on the Eiffel Tower were switched off in mourning and solidarity with the UK.
Three French teenagers on a school trip were among those injured in Wednesday's attack.
President Francois Hollande offered condolences to Mrs May for those who died and expressed his country's solidarity with Britain "in this tragic ordeal".
"The British and French services are in close contact to conduct the investigation," he added.
"We are all concerned with terrorism. France, which has been struck so hard lately, knows what the British people are suffering today."
Mr Hollande added that countries "must bring all the conditions to answer these attacks" and that "it is clear that it is at the European level, and even beyond that, that we must organise ourselves".
German Chancellor Angela Merkel said she learned "with sorrow" of Wednesday's incident and her thoughts were "with our British friends and all of the people of London".
"I want to say for Germany and its citizens: we stand firmly and resolutely by Great Britain's side in the fight against all forms of terrorism," she said.
Russian President Vladimir Putin said the attack underlined the need to pool global efforts against terrorism.
In a letter to Mrs May released by the Kremlin, Mr Putin said the "forces of terror are acting in an increasingly treacherous and cynical way".
He said: "It's necessary to unite efforts of all members of (the) international community to confront the terror threat."
He offered condolences to the families of the victims and wished a quick recovery to the injured.
Foreign ministry spokeswoman Maria Zakharova said: "We don't split terrorism into categories, we consider it as absolute evil. At this moment, as always, our hearts are together with the British people, we feel their pain and speak again about the need to confront that evil."
Turkish President Recep Tayyip Erdogan condemned the attack which came hours after he warned that Western citizens could be in danger if European nations persist in what he described as arrogant conduct.
In a series of tweets, Mr Erdogan said Turkey shared "the pain of the United Kingdom".
He wrote: "We stand in solidarity with the U.K., our friend and ally, against terrorism, the greatest threat to global peace and security."
Australian prime minister Malcolm Turnbull said the police presence at Australian Parliament House had been increased in response to the London attacks.
"Australia's heartfelt sympathy and resolute solidarity is with the people of the United Kingdom with whom we stand today as we always have in freedom's cause. Staunch allies in the war against terrorism.
"The attack on the British Parliament is an attack on parliaments, freedom and democracy everywhere."
New Zealand's prime minister Bill English said he had written to Mrs May to express support for her government and to offer his country's condolences.
Spanish prime minister Mariano Rajoy sent a telegram to Mrs May, saying: "An execrable terrorist act like the one that took place today is a reminder that we face complex challenges for the security of our societies.
"We must remain united against these type of threats that affect all of us equally and that know no barriers."
Israel, which has faced a wave of Palestinian attacks since 2015, expressed solidarity with the victims.
Deputy foreign minister Tzipi Hotovely said: "Israel expresses its deep shock at the terror attack in London and its solidarity with the victims and with the people and government of Great Britain.
"Terror is terror wherever it occurs and we will fight it relentlessly."
The Italian interior ministry said its security and intelligence chiefs were meeting in Rome for "an evaluation of the terrorist threat".
Interior minister Marco Minniti convened the Committee of Strategic Anti-terrorism Analyses following "the tragic facts in London".
Italian security was already on high alert for a European Union summit bringing bloc leaders to Rome on Friday for a meeting with Pope Francis at the Vatican, and a ceremony in the Italian capital on Saturday.
Five South Koreans in their 50s and 60s were among the 40 injured when they were caught up in a stampede of people trying to escape the attack, the country's Foreign Ministry said.
Four suffered broken bones and other injuries and a woman in her late 60s needed an operation for a head injury.
Romania said two of its citizens were wounded.
Chinese premier Li Keqiang said the attack was the first subject of discussion when he met Mr Turnbull in Canberra.
Mr Li said: "Together we send our condolences to the prime minister of the UK and together we condemn terrorism and we stand against all forms of terrorism. There cannot be continued instability in the world. We must cherish peace and stability."
China said one of its citizens was among the injured and urged Chinese nationals in the UK to avoid crowded areas or travelling alone at night