The central bank said last night that it had called on Mr Singh, the chief executive of Drew & Napier, 'to advise MAS on the implications of the legal issues raised by the lawyers acting in the Chapter 11 proceedings for Lehman Brothers'.

This follows Tuesday's warning by the Minibonds trustee - HSBC Institutional Trust Services Singapore - that the unwinding of the notes may be challenged by lawyers involved in bankruptcy proceedings over Lehman in the United States.

Minibonds series 1 and 5 to 10 of the notes have defaulted and will be unwound by three appointed receivers of the defaulted notes from PricewaterhouseCoopers (PwC) Singapore.

On Tuesday, the receivers said investors might have to wait at least two years or more for any resolution, given the legal complexities introduced by the notice from Lehman's lawyers.

MAS last month also called on Deloitte & Touche Corporate Finance to advise the central bank on the

Minibonds fiasco. Deloitte & Touche's services have also now been extended.

While the MAS has Mr Singh and the resources of Deloitte & Touche, the receivers from PwC are separately being advised by their own legal counsel.

Last night, the MAS also reiterated the trustee and receivers' warning that it may not be possible for any resolution to be reached within a short span of time.

'Nevertheless, MAS expects the trustee and receivers to pursue all appropriate avenues to protect noteholders' interests,' it added.

About 8,000 retail investors sank $375 million in Minibonds - only to see Lehman collapse on Sept 15.

Three other independent parties have been roped in by the MAS to ensure that the plight of these investors is not ignored amid potential cross-border legal battles.

On Oct 2, Mr Gerard Ee, Mr Hwang Soo Jin and Mr Law Song Keng were appointed by distributors of structured products such as Minibonds, Merrill Lynch Jubilee Series 3 LinkEarner Notes and DBS High Notes 5 to oversee their complaints handling processes.

All three said they were working closely with the financial institutions to ensure fair and prompt resolution of complaints by investors.