Singapore needs vast amounts of sand for its many land reclamation and construction projects and its eagerness to buy up sand from its neighbours has long been a source of friction.
Amid environmental concerns about the effects of sand dredging carried out on Singapore's behalf, Malaysia, Indonesia, Cambodia and Vietnam have all placed full bans or partial restrictions on the export of sand (see my story in The Economist).
Last month an NGO called Global Witness published an investigation that revealed how river sand was still being exported to Singapore from Cambodia in defiance of a Cambodian government ban.
Now The Star, a government-owned Malaysian newspaper, has revealed that sand is also being exported illegally from southern Malaysia across the straits to Singapore and sold on to Singapore's Housing Development Board.
Campaigners such as Global Witness argue that Singapore's appetite for sand and its willingness to turn a blind eye to the way it is procured is causing serious environmental damage and undermining the fight against corruption in sand-exporting countries such as Cambodia and Malaysia.
In response to the Global Witness report, Singapore's Ministry of National Development claimed that it was "not true" that the "Singapore government seeks to import sand without due regard to the laws or environmental impact" in source countries such as Malaysia.
But the government, which likes to promote its credentials as an innovator in the field of sustainable development, noted that "the policing and enforcement of sand extraction licences is ultimately the responsibility of the source country".
It appears as if the Singapore government is (pardon the pun) burying its head in the sand, hiding behind the fact that the export and import of sand is done on a commercial basis and that it is the responsibility of the vendors and the exporting nation to ensure that everything is above board.
The Malaysian and Cambodian governments ought to be doing more to rein in the corrupt officials who are allowing the illegal sand exports to continue on such a grand scale.
But, if Singapore wants to be taken seriously as a responsible regional partner and environmental innovator, it must also step up to the plate.
The government may save money in the short term by buying in cheap, questionably acquired sand but it will have to pay the price in the longer term of supporting environmental degradation and corruption in neighbouring countries.