More than $30 million in Cambodian sand exports registered by Taiwan appear to be missing from Cambodia’s customs records, according to data from both governments, marking yet another large-scale discrepancy in the Kingdom’s figures on the trade.

The huge inconsistency – Cambodian customs data show only 28,900 tonnes of sand sent to Taiwan between 2010 and 2016, while Taiwan registered 1.7 million tonnes in the same period – was highlighted by NGO Mother Nature in a video released on Monday evening.

Following the release, two activists for the organisation were yesterday arrested while taking photos of two suspected sand-bearing vessels anchored near Prek Khsach commune in Koh Kong province’s Kiri Sakor district.

Mother Nature founder Alex Gonzalez-Davidson said Dem Kundy and Hun Vanak were seized aboard their small boat in open waters near a special economic zone owned by powerful ruling party Senator Ly Yong Phat.

Gonzalez-Davidson said the large vessels appeared to be carrying silica sand – which is mined from the ground rather than coastal estuaries or riverbanks, as with other types of sand – and were ready to depart.

Yesterday afternoon, the chief of Koh Kong police’s minor offence office, Lay Meng Laing, said the pair were arrested and were en route to his office. He said he did not know why they were arrested.

“The provincial police chief ordered me to wait and get the two,” Meng Laing said.

Reached yesterday, Provincial Police Chief Sam Khit Vien claimed he was in Thailand and unaware of the arrest.

Gonzalez-Davidson said the revelations of discrepancies in the sand trade with Taiwan – which come hot on the heels of similar discrepancies with exports to Singapore and India – “proved” that illegal sand exports were “systematic”.

“It would be happening with government complicity. It would not be transported in bulk shipments unless someone is providing documents,” he said. “This is beyond an environmental and ecological issue; this is about fraud and tax evasion. This is an economic crime.”

According to Cambodian customs figures, released by Mother Nature last year, between 2010 and the end of 2016, the Kingdom exported 28,900 tonnes of sand, worth $275,605, to Taiwan.

However, Taiwanese customs figures, which are available online, record 1.67 million tonnes of Cambodian sand imports in the period, worth $35.9 million. Of this, the overwhelming majority – some 1.5 million tonnes – was silica sand, valued at $32 million.

The government came under fire last year for even larger discrepancies in its sand exports to Singapore. The city-state registered $700 million worth of Cambodian sand exports between 2007 and 2015, for which Cambodia’s customs agency had no record.

Cambodian authorities have struggled to explain the gaps, with a government “investigation” into the trade with Singapore concluding that there was no discrepancy.

Following the revelation, the Ministry of Mines and Energy (MME) banned sand exports from Koh Kong province, but later clarified that silica sand was exempt from the ban.

MME spokesman in charge of mining Yos Monirath and MME Secretary of State Meng Saktheara could not be reached yesterday.

Saktheara, however, told Radio Free Asia the difference in figures with Taiwan could be caused by differences in recording methods.

The shipping code used on the Cambodian customs document – 2505 – is the umbrella code for natural sands of all kinds, excluding sands bearing certain metals. Figures from the Taiwanese import registry match the shipping code, but add extra digits to distinguish between silica sand and other natural sands.

However, the minor difference in codes would not explain why Taiwan’s imports of just a single type of sand would so vastly dwarf Cambodia’s exports of all sand.

Customs and Excise Department General Director Kun Nhem declined to comment yesterday.