Cox murder leaves UK in shock, ugly EU campaign blamed

Finance minister George Osborne commended Cox's humanitarian work: "Jo fought to help the refugees from the Syrian civil war - she gave a voice to those whose cry for help she felt was not being heard."

German chancellor Angela Merkel called the attack "terrible and dramatic", but she added she did not want to connect the incident with the UK's vote next week on EU membership.

US presidential candidate Hillary Clinton called the murder “a violent act of political intolerance”.

Jo Cox, the 41 year-old Labour MP for Batley and Spen in northern England, was killed after being stabbed and shot in the street outside a library.

On Friday, the British Union Jack was lowered to half-mast at Buckingham Palace across from Whitehall, the UK government headquarters.

Campaigns for the Leave and Remain camps were both suspended until the weekend at least ahead of the 23 June ballot.

An improvised vigil was also held at Westminster Abbey on Thursday night for Cox, the first British politician to be murdered since the Irish troubles.

"Jo died doing her public duty at the heart of our democracy, listening to and representing the people she was elected to serve," Labour leader Jeremy Corbyn said.

Who is to blame?

The suspect, named as Thomas Mair, remains under police arrest.

Witnesses said he shouted "Britain first" as he attacked Cox. Neighbours described Mair, who is known to have had mental health problems, as "quiet and helpful”. But he also had ties with hard-right nationalist groups, British media reported.

While the motives of the 52 year-old suspect remain unclear, commentators and politicians across the UK blamed the political atmosphere of the EU referendum campaign.

On the day of her murder, staunch anti-EU MEP Nigel Farage unveiled a poster saying "The EU has failed us”, with a picture a long line of marching migrants that also said: "Breaking point".

A column in the British conservative magazine, Spectator said in the wake of Cox's murder: "When you shout BREAKING POINT over and over again, you don’t get to be surprised when someone breaks. When you present politics as a matter of life and death, as a question of national survival, don’t be surprised if someone takes you at your word. You didn’t make them do it, no, but you didn’t do much to stop it either."

The Guardian, a British daily, called the attack on Cox "an attack on humanity, idealism and democracy".

Cox had received death threats before for her pro-immigrant stance.

In her first speech as an MP last year in parliament she praised the benefits of immigration. “Our communities have been deeply enhanced by immigration, be it of Irish Catholics across the constituency or of Muslims from Gujarat in India or from Pakistan, principally from Kashmir”, she said.

She also backed a campaign to accept more unaccompanied children to the UK.

It remains unclear how the murder will affect the referendum outcome.

Some analysts speculated it could boost the pro-EU "Remain" campaign, which has fallen behind according to recent polls.

The markets seemed to agree with this analysis, as Britain's sterling currency rose against the dollar after news of the attack.