The number of Scots that want to breakaway from the UK has grown in strength as the latest poll shows that the gap between the 'Yes' and the 'No' vote is tightening.

According the the latest TNS poll, around 29% of Scots plan to vote for breaking the union when they are asked the straight "yes/no" question: "Should Scotland be an independent country?" on 18 September this year.

This is an increase of 1% from the previous month.

While the latest poll figures place the 'No' vote behind the 41% 'Yes' vote figure, there are still nearly a third of Scots that are undecided on whether they want independence or not.

"The increase in the proportion who claim they are certain to vote is an indication that more and more people are realising the importance of this referendum and are becoming increasingly engaged in the process," said head of TNS Scotland Tom Costley in a statement.

"Many undecided voters are telling us that they will definitely cast their vote, and how the campaigns address their interests is likely to have a big influence on the final outcome."

The TNS data, which polled 998 people, also revealed that significantly more Scots plan to vote in the referendum, with 74% compared to 65% in September 2013.

Scottish residents, aged 16 above, are eligible to vote.

Currently, around four million of Scotland's 5.3 million population are eligible to vote.