Key dates in Greek debt crisis

Here are some key dates in the Greek debt crisis, after Alexis Tsipras's Syriza party won a surprisingly strong election victory, securing a mandate to push through tough economic reforms demanded by international creditors.

 -- 2009 --

- October: The Greek government reveals that the national public deficit for 2009 was twice as big as thought at 12.7 percent of the country's output, instead of 6.0 percent. The figure is later raised again to 15 percent of gross domestic product (GDP).

- December: credit ratings agencies Fitch, Standard & Poor's and Moody's downgrade Greece's debt.

 -- 2010 --

- April: With public debt at 350 billion euros ($389 billion) and Greece essentially unable to borrow on debt markets, Athens appeals for aid from the European Union and the International Monetary Fund.

- May: Greece becomes the first eurozone country to receive a bailout as the EU and IMF agree to a 110-billion-euro package of loans in exchange for austerity measures that include wage cuts and tax hikes.

 -- 2011 --

- October: As Greece's economic situation deteriorates, the eurozone prepares a second loan package ultimately worth 130 billion euros. In addition, private sector creditors agree to write off more than 100 billion euros, about half the debt owed to them.

 -- 2012 --

- May 6: Two Greek political parties that accepted austerity measures, the socialist Pasok and conservative New Democracy, suffer losses in early elections. Fresh elections are held.

- June 17: The two pro-bailout parties form the core of a new government after a close vote. The conservative prime minister creates a three-party coalition.

 -- 2014 --

- April: Greece returns to sovereign debt markets for the first time in four years and posts a primary budget surplus (which excludes debt interest payments).

 -- 2015 --

- January 25: The Syriza party of Alexis Tsipras wins a snap election with a pledge to renegotiate the bailout terms. In five years, Greek GDP has fallen by 25 percent, salaries have withered and a quarter of the workforce is unemployed.

- February 20: Greece's creditors agree to extend emergency loans until the end of June. Athens vows to enact reforms in exchange for the last 7.2 billion euros in rescue funds.

- June 30: Greece's bailout officially expires and the country misses a 1.5-billion-euro debt payment to the IMF.

- July 5: More than 61 percent of Greeks reject creditors' bailout terms in a referendum.

- July 13: Greece and its creditors agree to preliminary terms of a third bailout deal in return for reforms that exceed those rejected a week earlier. Greek lawmakers approve a first batch of reforms on July 16 and 23.

- August 11: Greece and its creditors agree on fiscal targets for the third rescue package.

- August 14: Greece's parliament approves the bailout but a third of Syriza MPs rebel, forcing Tsipras to rely on the opposition for support. Later in the day, eurozone finance ministers formally approve the third debt bailout worth up to 86 billion euros.

- August 20: Tsipras quits and calls for new elections -- the country's fourth since 2012 -- with a bid to regain office with a strengthened hand. The announcement comes as Athens receives the first tranche of bailout cash from the EU's bailout fund, allowing it to repay a 3.4-billion-euro debt to the ECB on time.

- September 20: Syriza wins a surprisingly strong victory in the polls, and looks set to form a coalition with a small nationalist party, with a mandate to push through the reforms needed for the latest international rescue