Angela Merkel: "We must be sure to weigh the pros and cons"
Germany's Chancellor Angela Merkel has called the talks on Greece's debt rescue "extremely difficult" and ruled out "agreement at any price".
She was speaking as she arrived in Brussels for a meeting of the other 18 eurozone leaders to discuss the deal.
They are considering proposals by eurozone finance ministers which would impose tough conditions on Athens.
Greece risks being ejected from the eurozone if a deal to rescue it from financial collapse is not reached.
Finnish Finance Minister Alex Stubb said one condition in the ministers' proposal requires Greece to implement new laws by Wednesday.
Greece will also be required to introduce tough conditions on labour reform, VAT and taxes, and tough measures on privatisation and privatisation funds, Mr Stubb told reporters.
The head of the Eurogroup of finance ministers, Jeroen Dijsselbloem, said a "couple of big issues" remain which would be left to the heads of government to rule on, though he did not give details.
Greek PM Alexis Tsipras: "We can reach an agreement tonight if all parties want it"
Mrs Merkel told reporters that the eurozone leaders would be considering whether "the conditions are met" to start negotiations on a third bailout.
"That's what is at stake, nothing more and nothing less," she said.
But she warned that there would be "no agreement at any price", adding: "We have to make sure the pros outweigh the cons - for Greece's future, for the entire eurozone and the principles of our collaboration."
Mr Tsipras was more upbeat, telling reporters: "I'm here ready for an honest compromise... we can reach an agreement tonight if all parties want it."
The new austerity measures submitted by Greece include:
Prior to the finance ministers meeting, many had spoken of a breakdown in trust between Greece and other eurozone nations over the negotiations.
Reports on Saturday suggested that German ministers were drawing up a plan that would allow Greece to exit the eurozone temporarily if this weekend's talks fail - something Athens says it is not aware of.
This idea was also dismissed by France's President Francois Hollande who said: "There is no temporary Grexit, there is a Grexit or there is not a Grexit."
He said France would "do everything to find a deal tonight, allowing Greece, if the conditions are met, to remain in the eurozone and allowing Europe to progress".
Greece is asking creditors for €53.5bn ($59.47bn; £38.4bn) to cover its debts until 2018.
However, the amount of the new bailout could reach €74bn as Greece seeks a restructuring of its massive debt, which it says is unsustainable.
Of the €74bn, €58bn could come from the EU's bailout fund, the European Stability Mechanism, with €16bn from the IMF, sources have said.
The Greek government this week set out a new list of austerity measures to try to secure the bailout - many of which had been rejected by the Greek people in a referendum last Sunday.
As the talks drag on, Greece's financial situation is close to collapse.
Greece fell into arrears on an International Monetary Fund repayment on 20 June and faces a €3bn payment to the European Central Bank on 20 July.
Banks have been closed for two weeks and a €60 daily limit on cash machine withdrawals, imposed on 28 June, remains in force for Greek citizens.
Economy Minister Giorgos Stathakis told the BBC on Saturday that if there was a deal, banks could reopen within the week, but he admitted it could take a "few months" to remove capital controls.