Raising the firewall around the euro zone ever higher will only end up running into financial and political constraints, European Central Bank policymaker Jens Weidmann said on Wednesday, urging policymakers to address the roots of the bloc's debt crisis.

Weidmann, who also heads Germany's influential Bundesbank, added in a speech in London that whether we like it or not, we are also changing the rules of the game in monetary union and might set incentives that lead to new problems in the future.

His comments on raising the firewall around the euro zone are in direct contrast to remarks on Tuesday from the head of the OECD, who advocated the mother of all firewalls for the 17-country bloc to impress financial markets.

Weidmann said that ring-fencing the crisis with a firewall had been a sensible approach to stop it spreading, but just like the 'Tower of Babel' the 'Wall of Money' will never reach heaven... If we continue to make it higher and higher, we will, infact, run into more worldly constraints - both financial and political ones.

We must realise that all the money we put on the table will not buy us a lasting solution to the crisis, he added, saying all this did was buy time that must be used to address the root causes of the crisis.

Weidmann called for countries with current account deficits and excessive public debt to implement structural reforms and consolidate budgets.

(Reporting by Sakari Suoninen, writing by Paul Carrel in Frankfurt, editing by Marc Jones)