The European Union must "get a grip" of Greece's economic woes before the contagion spreads, ex-chancellor Alistair Darling has said.
In a gloomy assessment of Europe's economic prospects, Mr Darling told Sky News the EU had to find a solution to the problems in Greece.
He warned a failure to tackle the problem would have a "damaging impact" on European banks and governments.
"That's why the EU has got to be realistic and at long last do something that actually fixes the problem and not this series of short-term fixes that keep failing, that keep coming back," he told Jeff Randall Live.
"This is what they've been doing now for the last 18 months and it doesn't work."
Mr Darling offered the pessimistic analysis of EU economies in an interview also critical of former prime ministers Tony Blair and Gordon Brown.
Economic troubles provoked clashes on the streets of Greece.
He was speaking in advance of the publication of Back From The Brink, a memoir of his time as chancellor during the financial crisis.
The former chancellor said he had to elaborate on his fraught relationships within the government in order to tell the story of the turmoil that engulfed the markets in 2008.
He said Mr Blair and Mr Brown had been allowed to assume too much control.
"In the 1990s, we were happy in some ways to let Tony and Gordon run the show - it wasn't quite a dictatorship - they made the changes Labour was desperately needing to make but hadn't done so.
"The problem was the decision-making became increasingly centralised," he said, adding policies on tuition fees and the economy would have benefited from wider debate.
"Collective discussion, the benefit of getting a combined wisdom, is I think something we didn't pay enough attention to," he added.
The ex-chancellor explained his criticism of Gordon Brown.
Asked if Ed Balls was among those who unleashed the "forces of hell" in negative briefings about him during the financial crisis, Mr Darling refused to attack his Labour colleague.
He said he backed the whole Labour front-bench, including the shadow chancellor.
Mr Darling said he acknowledged Labour did not always get it right in government and expressed regret more had not been done to fully implement welfare reform.
He cited the minimum wage as one of his party's greatest achievements.
An MP since 1987, Mr Darling was chancellor between 2007-2010 and also served as secretary of state for work and pensions, transport and trade and industry.
His outspoken remarks since leaving office are considered to be a contrast to the more low-key style he adopted in government.