Greek Prime Minister Alexis Tsipras has vowed to push on with his plan for Sunday's referendum on the recent proposals from the country's creditors and accused them of 'blackmail.'

As crowds of elderly Greeks swamped banks to withdraw their maximum of 120 euro (£85) for the week, Mr Tsipras also reaffirmed his support for a No vote in referendum.

In a televised national address, the politician insisted that a "no" vote would not put Greece's place in the euro or in the European Union at risk.

Mr Tsipras said Europe must stop acting in an "undemocratic way" and sought to reassure Greeks that their bank deposits were safe.

It came as German Chancellor Angela Merkel is sticking to her position that there can be no negotiations on a new aid package before Greece holds its referendum.

"I have set out my position and I have nothing to add to it," she said after meeting with Italian Premier Matteo Renzi in Berlin.

Ms Merkel says her personal relationship with Greek Prime Minister Alexis Tsipras hasn't suffered and that she backs "the right of a sovereign state" to make its own decision.

However, she added that it is equally right for other countries to have their own positions.

Earlier, Ms Merkel said there can be no new Greek deal until after the referendum, a viewpoint that contrasts that of French President Francois Hollande.

Mr Renzi said he thinks a referendum is a "mistake" but that he respects the will of the Greek people.

The Greek government's attempt to kick-start talks on a new credit package got short shrift from euro zone finance ministers, who decided to put all discussion with Athens on hold until after the result of the poll.

They took the decision in a scheduled conference call that began an hour after Mr Tsipras spoke.

"There will be no further talks in the coming days, not at Eurogroup level, nor between the Greek authorities and the institutions on proposals or financial arrangements," said Dutch Finance Minister and Eurogroup chairman Jeroen Dijsselbloem.

He added: "We will simply wait now the outcome of the referendum on Sunday and take into account the outcome of the referendum."

On the streets, there were chaotic scenes as officials reopened some Greek banks to help pensioners who do not have bank cards.

With many pensioners unable to get their hands on funds without bank cards, the government said about 1,000 bank branches across the country would open for three days starting today to give them access to some cash.

But a seeming last minute decision to serve customers on an alphabetical basis led to chaotic scenes of confusion and anger, with many pensioners waiting for hours from before dawn to be eventually told they would have to return Thursday or Friday.

Others were told their pensions had not yet been deposited and they would therefore have to return later in the week.

Greeks are limited to ATM withdrawals of 60 euro (£43) a day and cannot send money abroad or make international payments without special permission.

It came hours after the country's bail out program with European creditors expired and it failed to repay a debt to the International Monetary Fund (IMF) - the first country to do so since Zimbabwe in 2001.

The expiry of its bailout and the missed IMF payment left Greece cut off from vital financing and pushed it one step closer to leaving the euro.

The eurozone's finance ministers are set to weigh a last-minute Greek proposal for a new aid programme, submitted on Tuesday afternoon.

On Friday, Mr Tsipras announced he would put a deal proposal by Greece's international creditors to a referendum.

The move increased fears the country could soon fall out of the euro currency bloc and saw Greeks rushing to pull money out of ATMs, leading the government to shutter its banks and restrict banking transactions.