More than half of voters say they do not understand the European Union Fiscal Treaty, according to a new opinion poll.

The Behaviour and Attitudes survey for tomorrow's Sunday Times also shows that the Yes side is leading ahead of the referendum on the treaty.

The poll was taken among 946 voters around the State over seven days, ending last Tuesday.

It has a margin of error of plus or minus 3.3%.

Asked how they would vote, 42% said they would vote Yes, while 27% would vote No, and 31% said they do not know.

When the undecided voters are excluded, the Yes side is ahead by 61% to 39%.

Asked how well they understood the Treaty, just 6% said they understood it very well, while 12% claim to understand it quite well, and 27% say they understand it "to some extent".

But 23% say they do not understand it particularly well, and 32% say they do not understand it at all.

That means that 55% of voters do not understand the Treaty, with less than six weeks to go before polling day.