The world financial system is as dangerously stretched today as it was at the peak of the last bubblebut this time the authorities are caught in a "policy trap" with few defences left, a veteran central banker has warned.

Nine years of emergency money has had a string of perverse effects and lured emerging markets into debt dependency, without addressing the structural causes of the global disorder.

"All the market indicators right now look very similar to what we saw before the Lehman crisis, but the lesson has somehow been forgotten," said William White, the Swiss-based head of the OECD's review board and ex-chief economist for the Bank for International Settlements.

Professor White said disturbing evidence of credit degradation is emerging almost daily. The latest is the disclosure that distressed UK construction group Carillion quietly raised £112 million ($195 million) through German Schuldschein bonds. South African retailer Steinhoff also tapped this obscure market, borrowing €730 million ($1.11 billion).