Officials have ordered enough independence referendum ballot papers for 120% of voters, amid expectations of a particularly high turnout in the poll to decide Scotland's future.

Spare voting papers are always needed at votes, in case any are destroyed or damaged.

Councils have also been told to bring in additional staff at polling stations to prevent hold-ups on the day.

A high turnout is expected to be a boost to the nationalists. Polls suggest those who support independence are more likely to vote than those who wanted to remain part of the United Kingdom.

Recent research suggests that a greater willingness to vote could be worth as much as two percentage points to the Yes side.

Announcing the arrangements for the vote, Mary Pitcaithly, the Chief Counting Officer (CCO) for the referendum, also confirmed the count would take place overnight on September 18.

She said: "My focus is on ­ensuring that all elements of planning and delivery of the ­Scottish Independence Referendum are undertaken with the interests of the voter at the heart of all decisions."

She added: "I believe these directions will inspire confidence and provide consistency in the process so that we can administer a successful referendum, with a result that everyone will trust as accurate."

She has also ordered that there should be one polling clerk for every 800 eligible voters.

Additional staff will also be expected to man polling stations at busy times.

Officials are keen to avoid the chaotic scenes witnessed in 2010, when queues led to people being turned away from poling stations and not allowed to vote in that year's General Election.

Under the plans announced yesterday, voters will see polling cards for the referendum start to drop through their letterboxes by the middle of August. Postal votes will be sent out on August 28.

Other directions sent out to counting officers include an instruction that ballot papers must be white.

Last night both sides of the debate said that they were pleased at the prospect of an extremely high turnout.

Sarah-Jane Walls, a spokeswoman for the pro-independence Yes Scotland, said: 'Given that on September 18 we will, as a nation, be making the most important decision ever about Scotland's future, we are delighted by the prospect of a high turnout at the referendum. As we move towards the regulated period of the campaign, it is clear that more and more people are engaging in the debate, and that is good for democracy and for Scotland.'

Meanwhile, a spokesman for the pro-Union campaign group Better Together said: "The more people who vote in this referendum the better. This is the biggest decision we will ever take in Scotland, so it's essential that as many people as possible get involved and make their vote count.

"We will be doing everything we can between now and polling day to make sure that as many people get out and vote for Scotland to stay in the UK."

Earlier this month researchers suggested the greater resolve of Yes supporters could give the pro-independence campaign an advantage on polling day.

Their study found the Yes supporters' determination could add two percentage points to the "Yes" tally.

The findings, from the ScotCen social research centre, also predicted overall turnout would be between 70% and 80%.

In addition, 90% of clear Yes supporters were more likely than not to cast their ballot, compared with 86% of clear No supporters.