Eurozone finance ministers told their Greek counterpart that Athens must go beyond an initial set of proposals for reforms if it wants them to open negotiations on a bailout, eurozone sources say.
Several sources said there was consensus among the other 18 ministers around the table during the "exceptionally difficult" talks that the leftist government in Athens must take further steps to convince them it would honour any new debts.
Greek officials, European finance ministers and leaders held talks in Brussels to decide whether to negotiate a third bailout for Greece to steer it away from imminent bankruptcy.
Al Jazeera's Neave Barker, reporting from Brussels, said Saturday's talks wrapped up "with a real sense of distrust coming from a lot of the Eurogroup".
A full summit of all 28 European Union leaders will vote on Greece's proposal on Sunday.
Earlier on Saturday, the Greek parliament backed a proposed bailout package with painful austerity measures from Prime Minister Alexis Tsipras’ government, with 251 of 300 MPs voting in favour of the package. Such harsh austerity measures were something his leftist party was elected to counter.
Officials have voiced concern over whether or not Greece can be trusted to stick to the proposed reforms, which include spending cuts in areas such as pensions and tax hikes, to secure a three-year bailout of $59bn.
"We are still far away. It looks quite complicated," said Eurogroup chairman and Dutch finance minister Jeroen Dijsselbloem.
"On both content and the more complicated question of trust, even if it's all good on paper, the question is whether it will get off the ground and will it happen. So I think we are facing a difficult negotiation," Dijsselbloem said.
Michel Sapin, the French finance minister, echoed Dijsselbloem's concerns, saying that trust was a major issue in the negotiations.
"Confidence has been ruined by every Greek government over many years which have sometimes made promises without making good on them at all," Sapin said, adding: "Today we need to have confidence again, to have certainty that decisions which are spoken of are decisions which are actually taken by the Greek government".
'Message of structural change'
Italian Prime Minister, Matteo Renzi, was optimistic and told Al Jazeera in Rome on Thursday - the day the reform proposals were sent to its eurozone creditors - that if the Greek parliament approved the proposal, "I think then next Monday Greece will be in the eurozone and the emergency for Greece will be solved."
He said: "The real challenge for Greece in this moment is give a message of structural change in the country."
There are international calls to give Greece some debt relief, and within the European body these have also come from European Council President Donald Tusk who will chair Sunday's emergency summit on Greece's future.
On Sunday eurozone leaders including German Chancellor Angela Merkel and French President Francois Hollande will meet to endorse the decision or to mitigate the fallout of a financial collapse, which could include humanitarian aid.
Banks in Greece have been closed for two weeks and if a deal is not reached when the markets open on Monday, some banks could collapse.
A “Grexit” would make Greece the first country to leave the eurozone and its departure would have unpredictable ramifications on both Greece and the global financial markets.
Nina Schick, a European policy analyst, told Al Jazeera that negotiations could be difficult when France and Germany had opposing positions, with Germany requiring more of Greece.
Shick said there were reports that France sent over a team of French experts to Greece to help Greek officials put together their latest offer, which did not impress Germany's Merkel, who wants harsher conditions.
Source: Al Jazeera and agencies