"We would like to inform you that we are seeking a new loan facility from the International Monetary Fund," Finance Minister Euclid Tsakalotos wrote in a letter to Christine Lagarde, the managing director of the IMF.
The debt-crippled Greek government, led by radical-left party Syriza, had initially planned to go without fresh help from the IMF as it considers the agency too wedded to draconian austerity measures.
Tsakalotos said Greece was taking new steps to move ahead with talks on the bailout -- which will be worth up to 86 billion euros (USD 94 billion) over three years -- after parliament passed two laws enshrining a series of tough reforms demanded by the creditors, including tax rises and a pensions overhaul.
"The Greek authorities have committed to implement a number of policies that would enhance fiscal sustainability, strengthen fiscal stability, sustain long-term growth and, importantly, spread the cost of economic adjustment in a fair way," the finance minister wrote.
"It is our belief that it will take several quarters before the Greek economy faces up to these challenges and returns to a vigorous and sustainable path to growth with fairness and social inclusion," he added.
Tsakalotos noted that Greece, which has previously been bailed out twice by the European Union, European Central Bank and IMF, has already formally requested a new three-year loan from the eurozone's bailout fund, the European Stability Mechanism.
Greece's existing aid programme from the IMF runs until early 2016, and a new request was not technically necessary.
The development came amid an apparent delay in getting the ball rolling on talks to finalise the package, with sources familiar with the matter speaking of "logistical problems".
Greece had said yesterday that negotiators would fly in to Athens on Friday to begin the talks, but by Friday the European Commission was saying representatives of the so-called troika of creditors would arrive "in the coming days".