Private holders of Greek debt have until later on Thursday to decide whether they will take part in a debt-cutting deal to save the country from bankruptcy.
Greece needs at least 75 per cent of bondholders to agree to take a 53.5 per cent cut in the value of their holdings by a 2000GMT deadline, if it is to receive a second bailout.
The package Greece is expected to receive from the European Union (EU) and International Monetary Fund (IMF) is worth $171bn.
However, Greece first needs the creditors to agree to the debt swap on the $270bn worth of Greek bonds they hold.
Bondholders are also being asked to accept a lower interest rate and give Greece more time to repay them.
Those who hold debt issued under foreign law have until April 11 to decide.
Greece would like to see 90 per cent of private creditors take part, and says it will not go through with the deal unless at least 75 percent do so.
The offer to exchange the old Greek bonds for the new ones expires late on Thursday but some investors are still holding out in the hope that they can find a better deal for themselves.
The EU economic and monetary affairs commissioner Olli Rehn has urged private holders to sign up to the debt swap deal.
"It is important that all investors recognise that Europe has committed the maximum funds available to this voluntary debt exchange and that full participation is necessary for the Greek programme to move forward," said Rehn.
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Late on Wednesday, the Institute of International Finance (IIF), which represents private creditors, said only about half of the creditors had agreed to the debt-cutting deal, even though details of the unprecedented swap have been hammered out during six months of talks between the Greek government and its creditors.
The Greek finance ministry has made it clear that the alternative to the debt swap is a potential default.
Greece and the IIF painted a dark picture of what the possible consequences might be if the country is forced into a disorderly default on March 20, when it is expected to pay $18.89bn of its debt.
An IIF report warned on Monday that if the debt swap deal failed, it could do serious damage to the eurozone and even the global economy.