THE brutal death of Labour MP Jo Cox could have a “significant effect” on the outcome of this week’s EU referendum, former first minister Alex Salmond said last night.

Salmond, now SNP foreign affairs spokesman at Westminster, said Cox’s death may even swing Thursday’s referendum towards a vote to remain in the UK.

His comments come as polls showed the Leave and Remain camps relatively neck and neck. This follows previous polling which put Leave ahead across the UK.

The former first minister also called for an end to what he claimed was “gutter” and “sewer” style campaigning from the Brexit side in the wake of the popular mum-of-two’s high-profile killing.

He said the “tragic” events surrounding the Labour MP dying from gunshot and stab wounds may give people “pause for thought”.

A number of other high-profile politicians, in a series of exclusive interviews with the Sunday Herald, also called for an end to inflammatory language and campaign tactics in UK politics, as part of a lasting legacy for the 41-year-old politician.

Salmond said the Leave campaign had been “poisonous”, pointing to a Ukip campaign poster unveiled by Nigel Farage that showed a long trail of migrants lining up to travel to the UK as evidence.

He attacked the Brexiters’ approach and said it had led to a heightening of tensions in society.

Salmond said it would be wrong to link the way the Leave side had conducted its campaign with the death of Cox last Thursday. However, he also suggested voters may choose to reflect on the events that saw the first killing of an MP in more than a quarter of a century.

When asked about cross-party calls for politicians to use less aggressive campaign language, he said: “I endorse that, but it’s about more than language. It’s about the nature of campaign negativity. The Leave poster of winding migrants was beyond the pale and these things do have an effect on the atmosphere. The Leave campaign has been poisonous and is a complete contrast with the way the pro-independence campaign was run.”

He added: “It would be wrong to attribute the tragedy of Jo Cox’s death with that – but the protagonists have an obligation to fight their campaigns in a particular way.”

Salmond, when asked whether the death of Cox could swing the outcome of the EU referendum towards Remain, said: “It might.” He added: “It might have a significant effect. But it should also have a long-term effect on cleaning our act up and getting out of the gutter.

“Hopefully it will concentrate minds and turn the page towards positive campaigning that doesn’t descend into the sewer. It’s difficult to say, but hopefully these events will make some people pause for thought.”

Salmond’s intervention came after the Labour MP’s bereaved husband, Brendan Cox, said that mainstream politicians had reinforced the right-wing populist view of immigration and had been “fanning the flames of resentment”.

However, a spokesman from the Scottish Vote Leave campaign hit back at Salmond and defended the way it had used the issue of immigration. The spokesman said: “These type of comments are unhelpful. Remain campaigners continue to dismiss voters’ concerns about immigration, yet we know the only way we can adopt a fair and balanced immigration (system) is by leaving. Immigration puts a strain on housing, hospitals and depresses wages of the poorest workers. We all believe immigration is beneficial but it has to be controlled, the only way to do that is by leaving the EU.”

First Minister Nicola Sturgeon also called for a “new beginning for our politics” in the aftermath of Cox’s death and for a shift in the tone of future political campaigns and debates, a view gaining momentum across most of the political spectrum yesterday.

Sturgeon said: “In so many ways Jo Cox was what all of us would want our politicians to be – somebody who was in politics to make a difference and do good for people.

“I hope the loss of Jo Cox’s life becomes a new beginning for our politics, where we are all inspired to rededicate ourselves to the notion of politics and public service as a force for good, and where we ensure that public debate about the many challenges facing us in the modern world – while sometimes rightly robust – is always respectful.”

Former prime minister Gordon Brown also called for a new “culture of respect” to challenge prejudice and intolerance after the death of Cox and warned that too often intolerance was descending into hate.

Meanwhile, grandees from the main parties including former Tory deputy prime minister Michael Heseltine, ex-Liberal Democrat leader Menzies Campbell and former Labour cabinet ministers Jacqui Smith and Tessa Jowell all called for a permanent shift in the way politics is conducted in the UK.

Jowell said: “If a legacy of Jo’s from this brutal murder is that in some small way there is change, then I hope that happens.”

Labour’s John Trickett, the shadow communities secretary in Jeremy Corbyn’s shadow cabinet, also called for an end to “inflammatory language” in political discourse, which he said had marred the EU referendum campaign.

Trickett, an MP for Hemsworth, a neighbouring West Yorkshire seat to the Batley and Spen constituency Cox represented, said: “Political debate has become coarsened and in some cases inflammatory language is getting used. I hope that the events of the last few days make everyone think carefully about how they express themselves. If that does happen it will be one of Jo’s many achievements.”

The’s SNP transport and islands minister Humza Yousaf, a high-profile campaigner against racism, paid tribute to the bravery of Cox’s husband.

Yousaf said: “If anybody deserves to be heard it’s Brendan Cox and you can’t fail to be moved by his comments. My view has always been that immigration should not be used as a tool to create fear.”

Former Lib Dem leader Menzies Campbell added: “A real measure of Jo’s influence would be just how long this tempered situation lasts for, as far too often after a pause we simply return to partisanship.”

One-time Labour home secretary Jacqui Smith added: “It would be a worthy legacy if political discourse was detoxified and the way we do things was changed.”

And Lord Heseltine, who served in the governments of John Major and Margaret Thatcher, echoing the calls for a rethink, said: “Of course I take the view that this is a shatteringly awful reminder that there are a very small number of people who can’t take the strain of debate.

“I’ve no doubt that her appalling murder will send a shudder through the political system and reverberate around the world.”