SSE, one of Britain's six big energy suppliers, said a planned referendum to decide on Scotland's independence from England had increased investment risk, although existing projects in the country would continue as planned.

Scotland's nationalist government, which already controls some spending from its own parliament in Edinburgh, wants to hold a referendum in late 2014 on full independence that could spell an end to a 300-year-old union with England.

The additional risk of regulatory and legislative change does not mean that SSE will not invest in projects in Scotland while its future is being determined, SSE said on Friday.

The development of SSE's existing projects in Scotland will continue as planned, the company said, but warned additional uncertainty would increase investment risk.

Perth-based SSE, which expects to spend close to 900 million pounds in Scotland in the year to March 31, 2012, employs more than 5,000 people in the country. It said it had no plans to move its headquarters out of Scotland.

Scotland already has its own legal system and devolved responsibility for health, education and emergency services.

Polls suggest between 30 and 40 percent of Scots support independence. The SNP hopes it can increase that by 2014, when national pride may be boosted by the 700th anniversary of the Battle of Bannockburn, a famous victory over the English.

Shares in SSE were down 1 percent to 1274.5 pence at 2:15 p.m.

(Reporting by Adveith Nair; Editing by Neil Maidment)