Tsipras tells lenders not to humiliate Greece over debt
Greece's prime minister has warned international creditors not to impose humiliating terms on his country as it seeks urgently needed bailout funds.
Alexis Tsipras said negotiations were at a "critical" stage, but that the lenders' proposals were "not realistic".
He was briefing parliament amid growing opposition in his leftist Syriza party to the creditors' proposals.
Earlier Greece delayed Friday's €300m (£216m) debt repayment to the IMF.
Mr Tsipras described the EU-IMF lenders' plan as a "bad moment for Europe" and a "bad negotiating trick".
He accused Greece's lenders of massively backtracking on measures agreed in recent months, and of failing to see the need for an end to austerity in their latest offer.
A call for debt relief was a key part of the Greek plan.
Greece in numbers
Greece's debt mountain
177% country's debt-to-GDP ratio
25% fall in GDP since 2010
26% Greek unemployment rate
The lenders' proposals were put forward when Mr Tsipras met the head of the eurozone's finance ministers, Jeroen Dijsselbloem, and European Commission President Jean-Claude Juncker in Brussels this week.
Denouncing their offer on Friday, Mr Tsipras said: "The strangulation of a country is a matter of moral order which conflicts with the founding principles of Europe."
He said the aim of any deal should be "for a solution and not to... humiliate a whole people".
He said his own proposals were the only "realistic" option.
Many of his own MPs are expected to object to any concessions by Athens.
All four scheduled repayments to the International Monetary Fund (IMF) in June will now be combined into a single payment at the end of the month.
Greece's schedule of repayments
Mr Tsipras said on Thursday that an agreement with Greece's international creditors was "in sight", particularly on the key sticking point of primary surpluses - the amount by which tax revenues exceed public spending.
But he said there were "points that no-one would consider as a base for discussion" - citing cuts to pensions and higher sales tax (VAT) for electricity.
Underlining a deep sense of anger among Syriza members, Deputy Social Security Minister Dimitris Stratoulis, who is close to Syriza's far-left faction, denounced the measures.
"If [the creditors] do not back down from this package of blackmail, the government ...will have to seek alternative solutions, elections," he told Antenna TV.
However, Finance Minister Yanis Varoufakis said on Thursday he saw "no reason whatsoever" for Greece to go to snap elections, according to Reuters.
Analysis - James Reynolds, BBC News, Athens
The Greek prime minister spent half an hour in parliament putting sandbags around his main demand: an end to austerity.
Alexis Tsipras said that he was disappointed with the proposals Europe has made this week.
The general outline of these proposals seems pretty clear: Greece should make further cuts and reforms. In exchange, it would get the money it needs to keep going.
But instead, the prime minister told parliament that his own counter-proposal, which protects salaries and benefits, should be accepted.
European capitals will not see it that way. Negotiators don't have all that much time left.
If there's no deal by the end of this month, there'll be no more bailout money for Greece.
Prime Minister Tsipras is understood to have spoken by phone on Thursday night with German Chancellor Angela Merkel and French President Francois Hollande.
He needs to decide soon whether to agree a deal with the creditors. Failure to do so could trigger a Greek default and a potential exit from the eurozone.
The government must now pay a total of €1.5bn back to the IMF on 30 June, which is also the day on which its bailout deal with the EU and IMF runs out.
However, the total this month Greece actually needs to pay in terms of bills is 6.7bn euros. The rest - 5.2bn euros - is short-term treasury bills.
Greece debt talks - main sticking points
- International creditors want pension cuts, slimmer civil service, VAT reform, fewer tax rebates and more private sector investment, reports say
- Mr Tsipras rules out increased VAT on energy and reduced supplementary payments for poorer pensioners
- Athens wants lower primary budget surplus targets, but both sides appear close to agreement. According to reports, creditors want a budget surplus of 1% of GDP this year and 2% next year, while Greece has proposed 0.8% for 2015 and 1.5% for 2016