Spain’s regulators believe that this approach need not be uniquely Iberian.

Madrid, some regulators now have a much gloomier message to impart. In recent months, the Bank of Spain has become convinced that off-balance sheet financial vehicles, such as conduits and structured investment vehicles, are likely to die a quiet death soon in global markets.

If the prediction is correct, it could give many banks around the world a jolt not least because the activities of the off-balance sheet vehicles have yielded rich pickings for the securitisation experts meeting in Vegas.

“If you look at the [International Financial Reporting Standards] rules, it is very clear that they mandate the consolidation of these [structured investment] vehicles,” José María Roldán, director of regulation at the Bank of Spain, told the FT.

“I would never expect conduits to come back [either],” said Mr Roldán. “They were like banks but without capital or supervision . . .There were ways to wind down conduits in an orderly fashion. The problem became the lack of liquidity. It was an extreme situation, and we are still in it.”

The unusually public comments are likely to be followed closely since they come at a time of intense debate in regulatory circles about the future shape of the banking system.

In the past two decades, most regulators have encouraged banks to shift assets off their balance sheets into SIVs and conduits since there was a widespread belief that this would make banks more resilient at times of crisis.

However, behind the scenes many regulators are now quietly rethinking this approach in light of the credit turmoil.

The Financial Stability Forum, a committee of regulators linked to the Bank for International Settlements, is due to issue a report on regulatory reform in the coming months, and this is likely to call for greater future scrutiny of entities such as SIVs.

“The Spanish experience is interesting . . . there is definitely a rethink under way now,” said one international regulator. Or as another US policymaker said: “There needs to be a way to have a more even treatment of risk across the system.”

The second reason why Mr Roldán’s comments will attract interest is that Spain has become something of a test case for an alternative regulatory approach in recent years.

When the subprime crisis exploded in the US last year, a majority of analysts predicted the contagion would soon spread to Spain. Spain, like the US, had an overheated housing market and banks that had lent freely into the construction boom.

Six months on, part of this prediction has played out, in the sense that Iberian banks are suffering from the effects of the liquidity squeeze, like the rest of the global banking system.

However, many analysts have been surprised to discover that Spain’s financial groups have had no exposure to the kind of mortgage-linked investment vehicles that have wreaked so much havoc in the US and Europe.

In the past few years, the Bank of Spain, which acts as financial regulator, has prevented banks from holding any kind of special purpose vehicles off balance sheet.

This conservative stance arose because Spain suffered a big banking crisis in the 1980s when financial groups that had built big industrial empires crashed under the weight of cross-shareholdings and intra-group lending.

“We learned early and the hard way,” Mr Roldán said. “Since then, we have always looked at risk from a consolidated perspective. Nowadays, this may sound like plain vanilla supervision, but before IFRS [was adopted in Europe in 2005], we were the first regulators to insist on the need to bring special purpose entities within the consolidation perimeter.”

He added: “In that respect you could say we have been lucky. Our experience has helped us.”

Spain’s regulators believe that this approach need not be uniquely Iberian.

As more countries and companies adopt IFRS, they should move to this pattern, too, if they adopt these accounting rules in full. “If the vehicle’s business looks very much like the business of the sponsor, it should be integrated. If the sponsor controls or benefits from the vehicle, it should be integrated. And if the sponsor assumes much of the risk, then it should be integrated,” Mr Roldán said.

“When reading IFRS in the context of what has happened, the rules are very clear.”

Whether the non-Spanish private sector bankers in Las Vegas will agree remains another issue.