According to the poll by the Alco institute on June 30 and July 1, after capital controls were introduced in Greece, 44.8 per cent intend to vote "Yes", 43.4 per cent are for "No" and 11.8 per cent of respondents are undecided ahead of Sunday`s referendum.

Meanwhile Greek Finance Minister Yanis Varoufakis says there`s a "100 per cent chance" Athens will reach an agreement with its international creditors after the referendum.

However, the survey had a margin of error of plus or minus 3.1 percentage points, meaning it was still seen as too close to call.

The figures nevertheless confirmed other polling results suggesting a swing away from the no vote urged by Greece`s left wing government towards the yes camp.

The survey was carried out on Tuesday and Wednesday this week, after Greece imposed capital controls.

Prime Minister Alexis Tsipras`s government is asking Greece`s voters to vote no to a technically phrased question asking if they are willing to accept more tough austerity conditions from international creditors in exchange for bailout funds.

But EU leaders say the plebiscite is really about whether Greeks want to stay in the eurozone or not.

They add that the question relates to a bailout package that is no longer available to Greece, having expired on Tuesday.

A no in the referendum would not strengthen Athens` position in talks with its creditors as the Greek government claims, EU Commission deputy president Valdis Dombrovskis said in a German newspaper interview on Friday.

"It would be wrong to think that a no would strengthen Greece`s bargaining position. The opposite is true," said Dombrovskis, who is the EU`s commissioner for the euro and social dialogue.

The situation for Greece was "substantially worse than it was a week ago" following the shock decision by Prime Minister Alexis Tsipras to call a referendum on the terms of his country`s bailout, Dombrovskis told the daily Die Welt.

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