Crowds gathered in central London for a special vigil to show solidarity with those affected by the Brussels attacks.
A 25-metre silk flag was stretched taut across the central staircase in Trafalgar Square ahead of the vigil, organised by the Mayor of London and the Belgian Embassy.
It follows similar tributes which saw landmarks including the National Gallery, Tower Bridge and the London Eye lit up in the red, gold and black tricolour on Wednesday.
More than 100 people gathered shortly after 6pm and flowers were laid next to the flag.
Some 32 candles were also lit in memory of the victims who lost their lives in the bomb blasts at Brussels airport and a metro station on Tuesday.
Belgian ambassador to the UK, Guy Trouveroy, said he had mixed emotions at the vigil, because despite the tragic events people had come together.
He said: "On the one hand we are sad, we hurt. This is a terrible tragedy that happened to us but at the same time we have a feeling of conference.
"We have some time to think about those who passed away, which is why we brought 32 candles representing the 32 people who have so far lost their lives."
Mr Trouveroy continued: "I think it's important because people are sad, people are lost, people are looking for some form of solidarity.
"Like in Brussels as we speak thousands of people are getting together, totally unknown to each other, by this grief that they have and by questions they are asking about 'go on earth can this happen?'
"Hopefully it shows that there is a resilience, there is anger, maybe not a sense of 'we want revenge' or hatred but definitely I think a resolve and commitment to fight and make sure this does not happen again."
Stephen Greenhalgh, London's deputy mayor for policing and crime, said: "It's important we show solidarity for the people of a sister capital city that we are not cowed by these terrible terrorist acts.
"And it's important London shows its support for the people of Brussels."
He added that the police presence at UK transport hubs and numbers of Metropolitan Police firearms officers had been boosted to reassure the British public.
"The counter-terrorism police are working together with security services to disrupt plots. They are arresting suspected terrorists at the rate of one a day," he said.
"We know that there is a heightened threat but there are a number of advantages over other capital cities and so far we haven't had a 7/7 since 7/7 and the police are doing a wonderful job along with security services to keep London safe.
"The golden partnership between the security services and the specialist counter-terrorism police ensure we are able to address the threats, whether it's in Kilburn or Kandahar, Peckham of Peshawar. That's one of the reasons we have been so successful in disruption terrorists up to now."
Among those attending the vigil were Quentin Martins and Natasja Bours, both Belgian nationals living in London.
Mr Martins said he was "totally shocked" but "not surprised" by the attack on his native country.
"Actually it was more an occasion of when not if. We were not prepared," the 33-year-old said.
As for the vigil, he said: "For me it's a bit sad we are only 100. I was expecting much more than that. I remember for Charlie Hebdo, I was here and it was a massive crowd. Maybe it's because it is raining."
But Miss Bours, 27, said: "It's important to meet some other people and have sympathy."