Stunned Britain puts EU vote campaign on hold after MP murder

Jo Cox was killed on Thursday outside a library where she regularly met constituents in her home village of Birstall in northern England

Campaigning for Britain's EU referendum next week was suspended on Friday for a second day as the nation reeled from the murder of a popular pro-Europe MP at the height of a bitterly divisive debate.

Jo Cox, a 41-year-old former aid worker and pro-EU campaigner known for her advocacy for Syrian refugees, was killed on Thursday outside a library where she regularly met constituents in her home village of Birstall in northern England.

Witnesses told local media the petite mother of two had been repeatedly shot and stabbed.

A 52-year-old man, named by media as local Thomas Mair, was arrested. Described by neighbours as a loner, there were indications that he had extreme right leanings.

With just six days left before the historic vote, rival groups campaigning for Britain to leave or remain in the European Union ceased campaigning and politicians joined as one to condemn the killing.

But some commentators questioned whether the murder could be linked to a campaign that has stoked high tension by touching on issues of national identity and immigration.

The Times newspaper reported, on Friday, that Cox, who became the first British MP to be murdered since 1990, had "had been harassed in a stream of messages over three months".

Police were considering putting in place additional security, it said, adding there was no known link between the messages and Thursday's attack.

Before Cox's murder, opinion polls were pointing to the likelihood that Britain would vote to leave the EU in the June 23 referendum, a prospect that weighed on financial markets and sent the pound tumbling.

The pound rose with Asian stocks today after the previous day's selloff, as investors judged the tragedy increased the likelihood of the "Remain" side prevailing.

US advocacy group the Southern Poverty Law Centre reported that Mair, who had lived in the area for decades, was a "dedicated supporter" of National Alliance, once the primary neo-Nazi organisation in the United States.

It said he had spent over $620 on reading material from the group, which advocated the creation of an all-white homeland and the eradication of Jewish people.

"Neighbours called him a 'loner' but he also has a long history with white nationalism," the Southern Poverty Law Centre said.

It added that Mair had purchased a handbook with instructions on how to make a gun, noting that witnesses told British media the assailant used a gun of "old-fashioned" or "homemade" appearance.