Up to 10 Scottish Labour MSPs could join the party's main Brexit campaign ahead of the EU referendum, IBTimes UK has learnt. Labour Leave, an offshoot of the Vote Leave campaign, made the claim after Kezia Dugdale's party said its 38 MSPs could have a free vote on the historic issue.

"We hope the UK Labour Party will follow this progressive line, given a lot of MPs who were put under pressure to join the 'Labour In' campaign actually support leaving the EU," a Labour Leave source told IBTimes UK.

"The EU has been a disaster for Scotland's fishing and agricultural industries. We are in discussions with a number of Labour MSPs who share our view that by leaving the EU we will regain control of our affairs and secure a better deal for Scotland and the rest of the UK."

When pressed on the exact number of MSPs likely to join the organisation, the source added: "We are briefing all MSPs on our position. In terms of support we are probably looking up to 10." Labour Leave has so far attracted the support of donor John Mills and Eurosceptic MPs such as Kate Hoey, Kelvin Hopkins and Graham Stringer.

The group plans to provide a left-wing case for a breakaway from Brussels and makes up part of the wider Vote Leave campaign, which is run by lobbying expert Matthew Elliott and one of Michael Gove's former special advisers, Dominic Cummings.

The organisation is currently competing with Leave.EU, which was co-founded by Ukip donor Arron Banks, to win the Electoral Commission's official Brexit campaign designation.

Meanwhile, former home secretary Alan Johnson has become the main figurehead of Labour's pro-EU campaign. The organisation will run separately from the Britain Stronger in Europe campaign after Labour was criticised for campaigning alongside the Conservatives as part of the Better Together group ahead of the 2014 Scottish independence referendum.

David Cameron is also expected to campaign to keep the UK within the EU but the prime minister continues to renegotiate with Brussels and has not yet set a date for the referendum. The Tory leader has only promised that the vote will be held before the end of 2017.

The latest online opinion poll from Lord Ashcroft, of more than 20,000 people between 20 November and 2 December, put "leave" on a nine-point lead over "remain" (47% versus 38%, respectively). But there has been a significant discrepancy between telephone and internet surveys around the EU referendum.