By Helen Reid

LONDON (Reuters) - Scotland wants to have more detail about how the British government plans to leave the European Union to prevent a "hard Brexit" that would severely damage the economy, Scottish First Minister Nicola Sturgeon said on Tuesday.

After Britain's vote to leave the EU, Sturgeon said Scotland may seek another independence referendum - something that could split the world's fifth largest economy apart just as it attempts to go it alone outside the European bloc.

A supporter of EU membership, the head of Scotland's devolved government said the Brexit vote showed deep voter disillusionment over free trade, immigration and what she said was unfair distribution of the spoils of globalisation.

Sturgeon said the Brexit vote in June had made it clear that a second referendum on Scottish independence was an option if the British government took decisions that hurt Scotland's economy and its place in the world.

"I'm trying to be tactful here - it would be helpful to know more about the UK government's kind of thinking," Sturgeon said in a speech to the Institute of Directors. "We would all benefit greatly from some clarity."

"I don't believe there is a clear mandate for what is generally known as a 'hard Brexit'," Sturgeon said, adding that it would hurt employment, business, investment and wider society by undermining institutions such as universities.

Under the 'hard Brexit' formula, Britain could be left without a deal on preferential access to the EU's single market and potentially grappling with soured relations with other EU members, while free to impose limits on immigration from the bloc.

Scots rejected independence in a 2014 referendum. But in the referendum on EU membership on June 23 they voted to stay in the bloc while England and Wales opted to leave.

"HARD BREXIT"?

The overall vote result took many investors and chief executives by surprise, triggering the deepest political and financial turmoil in Britain since World War Two and the biggest ever one-day fall in sterling against the dollar.

Despite warnings before the vote that Brexit would shatter economic confidence, some positive economic data and SoftBank's $32 billion takeover of Britain's technology company ARM have stoked the perception that Britain could prosper outside the EU.

Brexit will be more painful for the rest of Europe than for Britain which could emerge stronger and better off than its European neighbors, Mathias Doepfner, chief executive of Axel Springer, told the Financial Times.

But Sturgeon said she wanted to explore whether there were ways for Scotland to preserve the benefits of unfettered single market membership even if the rest of the United Kingdom did not get such market access in the Brexit process.

"We need to think creatively and negotiate constructively," she said. "No option can be off the table for Scotland."

Prime Minister Theresa May, who has repeatedly said that "Brexit means Brexit", has said she will not trigger the formal EU divorce before the end of the year and that she will then deliver the right Brexit deal for the United Kingdom.

May, who opposes Scottish independence, has said she wants Scotland to be fully engaged in the discussions about Brexit so that there can be a UK-wide approach.

Under the United Kingdom's complex arrangements to devolve some powers to Scotland, Wales and Northern Ireland, legislation generated in London to set off an EU divorce would have to gain consent from the three devolved parliaments, according to a report by the House of Lords' European Union Committee.

Sturgeon said she feared the end result of the Brexit negotiations.

"I do not want to see the UK government compound the mistakes of the EU referendum in negotiations and end up in a position that is much harder than we need," she said.

(Writing by Guy Faulconbridge; Editing by Richard Balmforth)