Labour leader Jeremy Corbyn has urged the public to "not allow hatred of any sort to take over" in the wake of the Westminster terror attack.
Speaking after he laid a floral tribute to those who died outside the Houses of Parliament, Mr Corbyn said that now was the time to "stand together" and try to "bring people together" following Wednesday's tragedy.
He said: "We have to stand together as a democracy and stand together to bring people together and not allow hatred of any sort to take over - I think that's the message."
More than £150,000 has been donated online for the family of police officer Keith Palmer, who was killed in the Westminster terror attack.
The 48-year-old was fatally stabbed outside at the Houses of Parliament by an attacker, named as Khalid Masood on Wednesday.
The Metropolitan Police Federation launched the Justgiving appeal on Thursday morning and it passed its initial £100,000 target within hours.
Multiple fundraising pages have been set up to help Pc Palmer's family, as well as other victims of the attack.
Theresa May has visited victims of the Westminster attack recovering in hospital.
A total of 29 people remain in hospital following the terrorist attack in London on Wednesday.
Following her statement to the House of Commons this morning, the Prime Minister spent around 40 minutes speaking to victims about their experiences.
Mrs May also spoke to medical staff, thanking them for their work, said her official spokesman, who declined to name the hospital where the private visit took place.
Many of those injured on Westminster Bridge were taken to St Thomas' Hospital, which faces the Palace of Westminster across the Thames.
Other victims were taken to King's College Hospital and the Royal London Hospital.
Police officers paid a solemn tribute to murdered officer Pc Keith Palmer on Thursday - the day after he was killed outside the Houses of Parliament by an armed attacker.
Pc Palmer, 48, was fatally stabbed while on duty during the Westminster terror attack on Wednesday.
Officers lined up outside Scotland Yard to remember Pc Palmer as the Metropolitan Police confirmed the officer's shoulder number - 4157U - will be retired and not reissued in future.
Foreign Secretary Boris Johnson said that the Westminster terror attack which killed three people on Wednesday was "an attack on the world".
Making the statement at the United Nations in New York, he said: "I can tell you from my talks here, that the world is united to defeat the people who launched this attack, and to defeat their bankrupt and odious ideology.
"I say that with confidence, because our values are superior, our view of the world is better and more generous, and our will is stronger.
"Our houses of Parliament in London have been attacked for centuries, by all sorts of people over the years, but the ideas embodied in those buildings, in that Palace of Westminster - freedom, democracy, equality of human beings under the law - they are stronger than any adversary, and they will prevail."
Asked whether there was anything that could be done with regards to radicalisation online, he said the responsibility lies with internet service providers and social media platforms, and that "everybody has responsibility".