Polls point to Greek Yes vote in bail-out referendum

More than half (60 percent) of those questioned said they believed Greece should remain part of the eurozone, no matter the cost. BNP Paribas has around €700 million in Greek debt.

The polls appear to show a public mood shift since the cash restrictions were introduced after the weekend, following Mr Tsipras's announcement of the referendum on the bail-out plan.

Frustration is growing over the clampdown on cash withdrawals in order to keep the banks solvent. People are only allowed to take out 120 euros or £85, per day, hitting shop sales and imports.

Eurogroup president Jeroen Dijsselbloem told MPs in the Netherlands that a No vote would almost certainly lead to a eurozone exit for Greece.

He told them: "I think that then there is not only no basis for a new programme. Then it is very doubtful if there is a basis for Greece in the eurozone."

Greek Finance Minister Yanis Varoufakis said he will resign in the event of a Yes vote.

Asked if on Monday there had been a Yes vote, he would still be in the post, Mr Varoufakis said: "I will not."

He also said he would not sign any deal with creditors without any reference to a restructuring of Greece's debt burden.

Mr Varoufakis claimed Greece was being treated as a "debt colony" that does not have rights.

However, he expected a "No" vote - and that he and Mr Tsipras will be around on Monday "to forge mutually beneficial agreement with rest of Europe".

It came as the head of the International Monetary Fund (IMF)Christine Lagarde reiterated her call for 'adulthood' in ongoing Greek debt negotiations.

Ms Lagarde told CNN it was the position of the IMF that Greece must pay back the money it owes the fund - and failed to pay as of Tuesday's deadline - saying that the country would not be allowed special treatment.

Ms Lagarde also told that until it agrees to meet its debt obligations, Greece is ineligible for any further funding. "We cannot finance any more until the international community, that is the IMF, is paid its due," she said.

Working out a strategy for Greece's debt burden, which stands at around 180 per cent of the country's annual GDP, is becoming a key discussion point ahead of Sunday's referendum on creditor proposals.

Many economists think Greece should get debt relief to allow the economy to breathe.

That could take the form of a reduction in the debt, extending repayments way into the future and slashing the interest rates payable on the debts.

Greece has had some relief when in 2012, the country's private creditors agreed a big write-down on their Greek debt holdings.

Meanwhile, one of Scotland's country's leading economists has hit out at the EU for attempting to impose austerity on Greece, as he claimed that being part of a UK monetary union would not stop Scotland adopting a Scandinavian model of high taxes and public spending.

Professor Brian Ashcroft, of the Fraser of Allander Institute at Strathclyde University, said he believed it should be for the Greek people to decide the balance between tax and spending, and that creditors' attempts to impose a target of a 3.5 per cent primary surplus by 2018 were "fundamentally wrong."

In a debate held this week, he said: "If external constraints say balance your budget, you can do it in several ways. But the Troike [a group of auditors representing the Commission, the European Central Bank and IMF] are arguing you have to do it through cutting public spending."

He later added that being part of a monetary union in Britain would not necessarily stop Scotland adopting a radically different tax and spend model than the rest of the UK, with control of income tax rates and some welfare powers set to be devolved to Holyrood.

Meanwhile, the German president's office says Greek President Prokopis Pavlopoulos has cancelled a planned visit to Berlin on Tuesday, where he had been due to meet German president Joachim Gauck.