THERESA May has attacked Nicola Sturgeon's independence "tunnel vision" as she insisted that what the First Minister should be doing as the Brexit talks approached was helping to bring people together rather than pulling them apart.

Speaking at a campaign event in yet another Labour marginal, Harrow West, the Prime Minister, surrounded by Tory candidates, urged activists against complacency and "not to take a single vote for granted". The Conservarives continue to enjoy an opinion poll lead of between 16 and 19 points.

Read more: Davidson urges voters to use election to cut the SNP "down to size"

She also pointed to the strong mandate Emmanuel Macron had received in the French presidential contest and insisted she needed just as strong a mandate from the British people at the General Election to ensure she entered he Brexit talks from a position of strength.

Asked why she thought the Brexit process would strengthen the Union and not Nicola Sturgeon's hand in seeking a second Scottish independence referendum, Mrs May said: "Now is the time we should be working together across the UK for the best result for the UK[in the Brexit talks] and not trying to pull apart.

"It's the tunnel vision of the Scottish Government in focusing only on independence that means they are not focusing on the work that needs to be done to ensure we get the best deal for the people of Scotland and the people of the UK as a whole."

Read more: SNP to spearhead national councils body for first time as cuts rows loom

Asked about the FM's criticism that her claim that certain people in Brussels were seeking to interfere in the election had "poisoned" the Brexit talks, the PM replied: "We have heard what is being said in Brussels and what that has shown us is that these negotiations are going to be tough; that means we need a strong negotiating position and the right leadership in the UK going into these negotiations."

Time and again during the campaign event, the Conservative leader posed a presidential question, saying the choice before voters was either to put her at the negotiating table with a team representing 27 other EU leaders or Jeremy Corbyn.

On immigration, she committed to keeping the Conservatives' target of reducing net migration to the "tens of thousands", saying this represented "sustainable levels".

Read more: Salmond predicts Tory boasts of a win in Gordon will backfire

The PM said it was important to hit this target given the pressure immigration had put on public services and those on lower incomes.

"It is important that we continue, and we will continue, to say that we do want to bring net migration down to sustainable levels.

"We believe that is the tens of thousands, and of course once we leave the European Union we will have the opportunity to ensure that we have control of our borders here in the UK, because we'll be able to establish our rules for people coming from the European Union into the UK."