Tony Blair today questioned the very survival of the euro unless growth is linked to fundamental reform in Europe.
The former British prime minister, who wanted to take Britain into the euro during his premiership, told the BBC Radio 4 World at One programme the only long-term solution was for Germany to stand fully behind the single currency.
But he said the Germans would be prepared to do this only if wide-ranging reforms were also delivered by European governments.
Mr Blair, who left office in 2007, also told the programme he would have accepted the presidency of the European Council if it had been offered in 2009 but that he was not currently seeking a position in European politics.
He told the programme: "The real difficulty you have got in Europe at the moment is people are being offered a choice between on the one hand austerity plus major structural reform, and on the other hand policies of growth and no reform.
"Actually, the only way you are going to get through this is to have a combination of policies that promote growth and at the same time with governments undertaking the deep structural reform Europe needs.
"This is the really difficult thing from Germany's point of view ... what we need in order for the single currency to survive is Germany has got to come fully behind the single currency.
"There has got to be no doubt about the depth of its commitment and its willingness to make the transfers necessary in order to preserve the single currency.
"However, it is completely unreasonable to ask the Germans to do this unless in return for that the reforms - which are in any event necessary for the European economy - are made."
Mr Blair said we were "very fast approaching" the point at which Germany will agree but only with "precise, credible demonstrations" the relevant reforms will be delivered.
"You only have to state that to realise it is a pretty big ask to make," he added. "But it is the only way, irrespective of what happens in Greece, that I can see the single currency now surviving."
Mr Blair said there was an urgent need to recapitalise European banks, potentially including those in France, but said growth was required for countries to deal with liquidity and solvency issues.
And he told the programme that whether or not the euro survives, and the former prime minister said he hoped it would, major political reform would be needed in Europe.
He said: "It is very, very important for us (in Britain) to be in a position where we can influence the shape of this political reconstruction which inevitably will happen almost irrespective of the fate of the single currency."
Asked if he would take a leading role in the reconstruction as an elected president, Mr Blair said: "That's way, way down the line.
"When the European presidency came up last time I would have taken it if the job had been offered but I've never thought of stepping back into European politics at this moment."