Thousands of people gathered in London and cities around the world today to commemorate British MP Jo Cox, whose killing last week shocked the country amid a fiercely contested campaign over the future of Britain's place in Europe.

Artists, friends and family members took to the stage in London's Trafalgar Square to praise a woman they described as a passionate campaigner for the rights of refugees and women.

Among those paying tribute were Nobel Peace Prize winner Malala Yousafzai, actors Gillian Anderson and Bill Nighy and singer Lily Allen, along with Cox's husband and sister.

"She just wanted people to be happy and the world to be a better place," Brendan Cox told a crowd of about 9,000, speaking on what would have been Cox's 42nd birthday.

BRITAIN-POLITICS/ATTACK

A woman holds a placard and white roses during a special service for slain Labour MP Jo Cox at London's Trafalgar Square on Wednesday. The memorial took place on what would have been Cox's 42nd birthday. (Peter Nicholls/Reuters)

His voice faltering at times, Brendan Cox said his wife had died because of her beliefs that included compassion for those fleeing the war in Syria, but that those beliefs would live on.

"Jo's killing was political," he said. "It was an act of terror designed to advance an agenda of hatred toward others. What a beautiful irony it is that an act designed to advance hatred has instead generated such an outpouring of love."

Cox was shot and stabbed to death on a street in her Yorkshire constituency last Thursday by a man who later gave his name in court as "death to traitors, freedom for Britain." The suspect is 52-year-old Thomas Mair.

Killing led to campaign pause

Cox's killing shocked Britain and triggered a three-day pause in campaigning ahead of Thursday's referendum on the country's EU membership — the so-called Brexit.

Her husband said the Labour Party lawmaker would have been campaigning for Britain to remain a member of the 28-nation bloc had she not been killed. "She feared the consequences of Europe dividing again," he said.

In a stark reminder of the political backdrop, a small plane flew by the square three times during the event trailing a banner bearing the words "Take Control, Vote Leave." It was unclear whether the plane intentionally buzzed the memorial and whether it was linked to the official "leave" campaign.

The event was broadcast live by video to several cities around the world, including Sydney, Paris and New York, where about 100 people gathered near the United Nations headquarters. Memorials also took place in Brussels and Ottawa.

Britain Lawmaker Killed

Many of those attending Wednesday's memorial said they had never met Cox but felt moved to come and express solidarity with her family. (Alastair Grant/Associated Press)

Cox was "impressive, smart, committed," said Lina Holguin, of Oxfam Quebec, in a statement. Holguin and Cox worked together at the humanitarian group years ago.

"Jo truly believed that it was possible to make the world a much fairer, peaceful and just place."

The statement from Oxfam includes an open letter, signed by more than 1,500 parliamentarians from around the world, including Canada, calling for tolerance and diversity.

"We must as societies stand together to stem the poisonous rising tide of fear and hate that breeds division and extremism," the letter says.

The Canadian signatories include NDP MP Nathan Cullen, who lauded Cox's work and life in a tearful address to Parliament last week.

#LoveLikeJo

Because Wednesday's gatherings marked what would have been Cox's 42nd birthday, 42 white Yorkshire roses were laid in Trafalgar Square.

Some in the crowd held up placards with the phrase "#LoveLikeJo" and many wept during a minute's silence and as videos were shown on a large screen from Cox's life.

Yousafzai, who referred to Cox as her "sister," said the response to the lawmaker's death mirrored the sympathy she received after being shot while campaigning for girls' right to education in Pakistan.

"Once again the extremists have failed," she said.

BRITAIN-POLITICS/ATTACK

Malala Yousafzai referred to Cox as a "sister" during Wednesday's memorial service. (Toby Melville/Reuters)

Many of those attending the memorial said they had never met Cox but felt moved to come and express solidarity with her family.

"This was a terrible thing to happen to any human being," said Hindi el-Fadel. "She just represented humanity, dignity."

El-Fadel said Cox's killing showed how polarized political debate in Britain had become lately.

"It's just really for me a reflection of the state of people's minds."

With files from CBC News