bringing cash personally into Singapore

[jpatokal]

A word of advice if needed; it is illegal to import Singapore dollars, Indian Rupees, or the Indonesian currency (rupias?) into Singapore.

This was the information supplied by the Royal Mail; hardly difficult to understand is it?

So, this interested me enough that I went to the proverbial horse's mouth, and here's what MAS has to say:

Dear Sir

I refer to your email dated 5 September 2007.

You may wish to note that there are no capital controls in Singapore.
However, we understand that under the Universal Postal Union arrangements which apply to all post offices, there are certain prohibitions for sending currencies via mail if they are not insured. You may wish to make enquiry with the post office in the country where you are mailing the currency, on the specific prohibitions.

Regards,
Kate Wong
Monetary Authority of Singapore

So there. Royal Mail may prohibit sending cash by mail, but Singapore does not, period.