The SNP are set to make major gains in next month's general election, an STV News poll has found, with the party surging at the expense of both Labour and the Conservatives.

An Ipsos MORI survey for STV gives Nicola Sturgeon's party an 18-point lead over their nearest rival, the Conservatives - on 44% to the Tories' 26%.

With two weeks to go until December 12, it is the largest lead given to the SNP in any Scottish poll since the campaign proper began.

The Ipsos MORI poll draws a stark contrast among Scottish voters compared to the rest of the UK, suggesting the Tories could lose half their Scottish seats next month even as they seemingly cruise toward an overall majority UK government.

A YouGov poll released earlier this week suggests Boris Johnson's party are heading for a comfortable majority that will allow them to break the parliamentary logjam created by the last election's hung parliament.

Emily Gray, managing director of Ipsos MORI Scotland, said the pollster's findings were "positive news" for Nicola Sturgeon.

But she cautioned that the "key issue" for the SNP remains ensuring their voters come out on polling day.

Labour is sitting in a distant third among those polled for STV News, with just 16% of voters in Scotland saying they will vote for Jeremy Corbyn's party, while 11% of respondents indicated they will vote Liberal Democrat.

According to Electoral Calculus, if these results were replicated on election day, the SNP could pick up an additional 13 seats, reaching the party's second highest ever total of 48.

However, the Conservatives would slip from 13 to six and Labour-held seats in Scotland would fall from seven to one, while the Lib Dems would stay on four.

The Scottish Greens are on 2% in the Ipsos MORI poll, with the Brexit party on less than 1%.

Based on the parties' showings in the election in 2017, the SNP have increased their vote by 7% while the Conservatives have dropped 3%, Labour are down 11% and the Lib Dems are up 4%.

The fieldwork for the survey of 1046 Scots was carried out between November 19-25, a seven-day spell which included the launch of the Tory, Labour and Lib Dem UK manifestos.

It also coincided with the first leaders' debate on ITV between Johnson and Corbyn last Tuesday, and the BBC's Question Time special on Friday featuring the two leaders as well as Sturgeon and Lib Dem leader Jo Swinson.

Ms Gray said: "It's positive news for the SNP - it has them on 44% of the vote and we know the Scottish public has a relatively favourable view of Nicola Sturgeon.

"The key issue for the party is, can they get the vote out on polling day. We know, for example, that many young voters like the SNP, so they need young people to turn out in sufficient numbers.

"The last two elections are a good indication: in 2015, when they did turn out, the SNP did very well, but in 2017 when they didn't, the SNP fell back."

STV's special correspondent Bernard Ponsonby said the Ipsos MORI results would "put a spring in the step" of the nationalists but have other parties "gargling with gin before the witching hour".

In further good news for the SNP, the STV poll found the country split precisely down the middle on the question of independence.

48% of Scots said they would vote Yes if an independence referendum was held tomorrow, and 48% said they would vote No, with 4% not sure.

Stripping out undecided voters, the result is a 50-50 split.

But the survey suggests people in Scotland are not yet behind the First Minister's proposal for a fresh independence vote next year.

Our poll indicates only a third strongly support holding one in 2020, with another 9% saying they "tend to support" the proposition.

However, a total of 50% of Scots say they either strongly oppose (43%) or tend to oppose (7%) a plebiscite next year, as Sturgeon would wish.

Ms Gray said the result showed the independence question is currently "too close to call".

But she added: "What we are hearing from people is that more of them don't want a referendum next year than do want one."

Ipsos MORI polling also finds the FM is the most popular party leader north of the border, with 48% satisfied with how she is doing her job compared to 48% unsatisfied, giving her a net-zero approval rating.

By contrast, just 22% of Scots are satisfied with how Boris Johnson is doing his job, with 74% dissatisfied, meaning he has net approval of -52.

Jeremy Corbyn has the same percentage of people satisfied with his job - 22% - but has only 69% saying they are unsatisfied with him, giving him a marginally better net approval than the PM of -47.

Meanwhile, the best-performing Scottish leader besides Sturgeon, in the eyes of those surveyed, is the Lib Dems' Willie Rennie with a net approval of -7, but his UK party leader Jo Swinson is on -21.

On the overall results, STV's Bernard Ponsonby said: "This is the most up-to-date snapshot and is therefore the one that will please the SNP and depress to varying degrees the other parties.

"But remember it is only a snapshot not a firm prediction of what will happen in two weeks time.

"Politicians for all they can be dismissive of polls secretly worry about them with their ability to gnaw at the very confidence they exude at election time.

"Our poll will put a spring in the step of some and have others gargling with gin before the witching hour."