EDINBURGH: Scottish nationalists are launching an official “yes” campaign on Friday ahead of a referendum on independence from Britain that is not likely to be held until 2014.

The “Yes Scotland” drive which will kick off in Edinburgh features the Scottish National Party of First Minister Alex Salmond and other parties including the Greens.

The launch at a cinema in the Scottish capital comes despite that a date has not been finalised for a vote on whether to sever the more than 300-year-old political union between England and Scotland.

Salmond wants the referendum in late 2014 and has proposed to offer a third option of increased devolution. The British government favours a swifter in-or-out vote.

“This has to be the biggest community-based campaign in Scotland's history,” a Yes Scotland spokesman said.

“We have a 550-seat venue full to capacity and we could have filled it again with the level of interest we have received.”

A pro-union campaign is expected to be launched later this year.

The Scottish government already has powers over some policy areas such as health and education for the nation of 5.3 million people, but defence, energy and foreign affairs remain with London.

Opinion polls show that around a third of voters in Scotland currently back independence, although the figure has risen in recent months.

British Prime Minister David Cameron has vowed to fight to keep Scotland in the United Kingdom.

Scottish independence would raise a host of issues including what happens to revenue from North Sea oil reserves and whether Scotland would become a republic or keep Queen Elizabeth II as monarch.