With a default looming, Greek Prime Minister Alexis Tsipras told state television that he was ready to talk to European negotiators to rescue a deal needed for Tuesday - when the European portion of Greece's bailout expires and Athens needs to pay 1.6 billion euros to the International Monetary Fund (IMF).

"My phone is on all day long. Whoever calls, I always pick up," Tsipras said. He suggested Athens could default, saying "(How) is it possible the creditors are waiting for the IMF payment while our banks are being suffocated?" adding: "Once they decide to stop the suffocation, they will be paid."

Tsipras also said that the result of a planned referendum on a proposed aid deal with Greece's European creditors - the EU Commission, the IMF and the European Central Bank - would be respected, but that his government would not be the ones to implement it.

"If the Greek people want to proceed with austerity plans in perpetuity, which will leave us unable to lift our heads ... we will respect it, but we will not be the ones to carry it out," Tsipras said. Hinting that he could step down if the referendum passed, Tsipras said he was not a prime minister who would remain in place "in all weathers."

The Greek prime minister had urged his fellow citizens to reject the terms of an aid deal proposed by Greece's international creditors in an upcoming July 5 referendum, dismissing fears that a "no" vote would see Greece depart from the eurozone.

"I don't think that their plan is to push Greece out of the euro but to end hopes that there can be different policies in Europe," Tsipras told Greek state television, adding that a rejection of creditors' terms would strengthen Athens' hand in subsequent negotiations.

Mass protests

As the drama continued to unfold Monday, thousands of defiant Tsipras supporters took to the streets of Athens, accusing Greece's creditors of blackmail.

At least 20,000 protesters gathered on the main avenue in front of the Greek parliament to voice their opposition to the latest potential bailout deal.

"Our lives do not belong to the creditors!" read placards held high by protestors. Other banners simply said "no!" and "Don't back down."

Ratings cut further

Meanwhile, ratings agency Standard & Poor's downgraded Greece's credit rating further into junk territory on Monday, from CCC to a CCC-.

"We interpret Greece's decision to hold a referendum on official creditors' loan proposals as a further indication that the Tsipras government will prioritize domestic politics over financial and economic stability, commercial debt payments, and eurozone membership," said S&P.

Ratings agency Fitch also announced Monday it had cut its ratings on four major Greek banks to "restricted default," citing "exceptionally high levels of credit risk."

The four banks targeted for the downgrade were National Bank of Greece, Piraeus Bank, Eurobank Ergasias and Alpha bank.

bw/jr (AP, Reuters, dpa, AFP)