Corruption has become an entrenched part of the global economy, says a report by Transparency International, with the eurozone debt crisis exposing the degree of corruption in nations at the centre of the financial meltdown.

Despite the efforts of campaigners in different parts of the world, Transparency International’s corruption perception index (CPI) shows that of the two-thirds of 176 nations surveyed had a score below 50, which means they are very corrupt.

Greece’s ranking in the 2011 survey stood at 80. This year the debt-hit nation slipped to 94 in the global league table - making it the most corrupt nation in western Europe.

Sadly, news that Greece is last among European Union countries on Transparency International’s Corruption Perceptions Index is not surprising. The emerging tax evasion cases, the scandal of people falsely declaring themselves blind on the island of Zakynthos, and the drama over the leaking of the “Lagarde list” of tax evaders have hit the headlines around the world.

Not only is Greece the lowest ranked EU country in an index that measures experts’ perceptions of public sector corruption: in 94th place, it ranks a massive 19 places behind the next EU member state, Bulgaria.

Greece is not alone in Europe in needing to wake up to corruption. Portugal and Spain share the same weak oversight of public spending, with auditors too weak or lacking independence from government. Many European countries do not oblige political parties to disclose donations from companies, are lax in regulating the way businesses lobby politicians and officials, or lack scrutiny over governments tendering of contracts to businesses.

Greece’s low rank tells a story. It illustrates the “crisis of values” that is driving the economic crisis, according to a report on corruption risks in Greek institutions published earlier this year.

The lack of accountable leadership – together with the deficit of transparency in the management of public finances and public spending – left us exposed to risk-taking and exploding debt, which brought us to today’s crisis.

To a large extent, Greece’s economic future depends not only on bailouts, but on how well it fights corruption. Bribery, tax evasion and a host of other mistakes have contributed to the present crisis Greece faces, and threaten to block any economic route the country takes in the future – default, bailout, austerity or stimulus.

When Transparency International assesses Greece’s institutions, we see flaws, but also positives that show corruption can be tackled. Greece’s ombudsman, for example, is well equipped to combat corruption.

Corruption can be tackled, but the reforms must run deep.

We live in an era where there is a rising tide of public demand for leaders to be more accountable for their actions. Time and again we are seeing leaders who fail to respond to that demand swept from power.

It is time for leaders to step up, lead by example, and cultivate a culture of integrity.