German Chancellor Angela Merkel has said there is still no basis for talks on a new Greek bailout, as she arrived in Brussels for an emergency summit of eurozone leaders.

"We still do not have the basis for negotiations" for a new aid programme with the EU's bailout vehicle, the European Stability Mechanism, she told reporters on Tuesday ahead of the summit called in the wake of Greece's "No" vote in a referendum on austerity.

Merkel said the leaders would discuss how to proceed, but "we will not be able to get a final picture. Though I have to say that it is not a question of weeks any more, but a question of a few days".

Earlier, Merkel held talks with Greek Prime Minister Alexis Tsipras, French President Francois Hollande and European Commission head Jean-Claude Juncker ahead of the wider summit of 19 eurozone leaders.

Greece is expected to make a formal request for a new bailout programme on Wednesday, Eurogroup chief Jeroen Dijsselbloem said, after a meeting of finance ministers from the eurozone earlier on Tuesday.

A Greek government source also said that a new pitch would be made over the next 48 hours, and that Athens has made improvements to the proposals for a bailout deal made to its creditors last week.

Greece last week defaulted on a $1.8bn repayment to the International Monetary Fund (IMF), and on Sunday, in a referendum, the Greek people voted to say "no" to the most recent bailout offer.

As leaders of the European Union gathered in Brussels on Tuesday, strong words have been directed against Athens, with Ilmars Rimsevics, Latvia's central bank governor, saying Greece has voted itself out of the eurozone after Sunday's referendum.

Tuesday's meetings have been billed as a last chance for Greece to stay in the single currency bloc. The country's banks remain closed and are down to their last reserves of cash.

Al Jazeera's Jacky Rowland, reporting from Brussels, quoted European officials as saying that the latest talks are "the end of the road" for Greece.

'Under siege'

On July 28, the Greek government has to pay another $3.8bn it owes to Europe Union institutions.

Tsipras has insisted that instead of a Greek exit, Greece's creditors will now finally have to talk about restructuring the country's massive 240 billion euro ($267bn) debt to them.

Greece's banks are fast running out of cash with officials in Athens announcing on Monday that the banks would remain closed until Thursday.

The daily withdrawal limits were to remain unchanged at 60 euros ($66) per account daily.

Al Jazeera's John Psaropoulos, reporting from Athens, said Greek banks were now operating "under siege," with one major Athens bank only able to keep its ATMs open on Monday after two major companies deposited their payrolls in cash.

The ECB has maintained its emergency liquidity lifeline for Greek banks, however it raised charges on collateral the banks require to present for funds, effectively devaluing the banks' assets and making them less able to borrow against their collateral.

"The situation is becoming financially worse, not just more politically difficult," Psaropoulos said.

Rapid negotiations

Tsipras on Tuesday must persuade Europe's other 18 leaders, many of whom are exasperated after five years of the Greek crisis, to open rapid negotiations for a major new loan to rescue his country.

Tsipras also spoke to IMF chief Christine Lagarde "on the need to find a viable solution dealing with the real problems of the Greek economy", the source said.

Lagarde said the IMF was "ready to assist Greece if requested to do so", despite the June 30 default.

European Commission head Jean-Claude Juncker said on Tuesday that while he did not want Greece to leave the eurozone, in a so-called Grexit, the Greek people had voted on a deal that "no longer existed".

"We have to put a very large ego away and deal with the situation we face," Juncker said.

Source: Al Jazeera and agencies