Singapore asked Indonesia on Monday for an update on the fate of granite shipments bound for Singapore's booming construction industry that the Indonesian navy detained last month, according to the AP.
The detention of the tugboats and barges in late February came soon after Indonesia banned exports of sand used to make concrete for resource-poor Singapore on Jan. 23. Indonesia cited environmental concerns and fears that sand exports could shrink Indonesia's borders.
But there has been no ban on exports of granite, and the detention of the vessels has become another irritant amid the sometimes testy relations between the two neighbors.
The Singapore statement said Indonesian Foreign Minister Hassan Wirajuda had assured his Singapore counterpart, George Yeo, on March 15 that a government team was investigating the detention of the tugboats and barges.
The foreign ministry sent a diplomatic note to the Indonesian Embassy in Singapore on Monday to seek an update on the results of the Indonesian team's investigation, the statement said.
During that period, Indonesian Fisheries and Maritime Affairs Minister Freddy Numberi was also quoted as saying his government would not resume sand exports until Singapore settles border disputes with Indonesia.
Indonesia is the main exporter of sand to Singapore, and its ban has sent shares in Singapore's construction companies plummeting amid speculation that Singapore would have to import concrete sand from more expensive sources.