Britain's turbulent experience divorcing from the European Union means there are no longer questions about other countries trying to leave the bloc, ECB policymaker Francois Villeroy de Galhau has said.

"It is a gratitude we have to the British today," Francois Villeroy told a panel at the London School of Economics.

Mr Villeroy also said that euro zone countries should consider easing taxes or boosting investment to support growth if their finances allow, singling out Germany and the Netherlands. 

In the face of slowing euro zone growth, the European Central Bank last week cut interest rates deeper into negative territory and promised bond purchases with no end-date.

In the speech in London, Villeroy said governments also had a role to play in kick-starting a recovery, echoing an appeal from ECB chief Mario Draghi last week. 

While there was still a need for growth-boosting nationa lreform programmes, he said "the euro area should now exploitits fiscal leeway - for instance in Germany and the Netherlands - to support growth."

"It is essential to choose qualitative expenditure (starting with investment) or tax cuts that have a strong impact on long-term growth," Mr Villeroy stated. 

Despite the urgency of reviving euro zone growth, Francois Villeroy said the bloc should not lose focus on other priorities like improving access to finance for small and mid-sized firms and venture capital or increasing the international role of the euro. 

He also poured cold water on calls for a climate change-focused quantitative easing programme, saying such a move would heavily distort the green bond market. 

France's central bank governor Francois Villeroy de Galhau said there had been suggestions for "green quantitative easing" - introducing a bias towards green assets in the ECB's purchase programme framework. 

"Despite its apparent simplicity, this proposal is incomplete and has serious limitations," Mr Villeroy said. 

He stressed that monetary policy targets a macroeconomic objective in the form of inflation and does not single out specific social or sectoral objectives. 

"Massive purchases on a relatively shallow pool of green bonds could seriously distort the market," he added. "I prefer a more 'integrated' and holistic approach." 

Villeroy, one of the founding members of the central bank Network for Greening the Financial System (NGFS) said climate change is a source of financial risk.

"It can also provoke both upward price pressures and a slowdown in activity - and can thus generate a long-term stagflationary shock," he added. 

Stagflation is where persistently high inflation combined with high unemployment can cause an economy to stagnate.

The ECB policymaker said that central banks should contribute to global efforts to understand and anticipate the economic effects of climate change and integrate the information into their macroeconomic models. 

They could also change the mix of assets they accept as collateral for their cheap funding, potentially giving preferential treatment to green bonds or penalising bonds or loans used to fund things detrimental for the planet's health. 

"This requires the development of a robust methodology to accurately assess the impact of climate change on the credit risk of eligible assets," he stated.