A regional illegal logging crisis that has driven a crime wave across the Mekong Basin can be combated by mooted high-level agreements aimed at protecting the most targeted timber species, an environmental monitor has said.

Meeting last week in Brunei, government representatives to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) were urged to close a loophole in the treaty that has allowed the continued export of endangered Siamese rosewood without permits.

Two other species heavily targeted in Cambodia should also be added to the list: Burmese rosewood and Burmese padauk, locally called neang nuon and thnong, the Environmental Investigations Agency (EIA) said.

At present, Siamese rosewood – known to fetch tens of thousands of dollars per cubic metre when sold in China – can be exported with only minimal processing, which “funnels both illegal and legal Siamese rosewood unhindered into regional markets”.

“With even the roots of Siamese rosewood trees being illegally harvested for export, border officials struggle to determine how to apply” the rules, the EIA said in a statement.

Adding thnong and neang nuon to the list of species requiring a permit from CITES was “justified as [they are] replacements to Siamese rosewood, but also in their own right as standalone species in danger of extinction from illegal and unsustainable trade”.

“As Siamese rosewood has become virtually depleted in the wild and some trade is restricted through limited CITES controls, lookalike replacement species also valued in the [Chinese] furniture market are now being systematically targeted and unsustainably harvested,” the EIA said.

Thnong is now thought to be the species most targeted in Cambodia, as Siamese rosewood stocks have been all but depleted by decades of industrial-scale logging.

Ty Sokhun, a secretary of state at the Ministry of Agriculture who heads Cambodia’s CITES management authority, said he was unaware of the meeting in Brunei last week and declined to comment on whether the proposed changes to the convention should be made.

In February 2013, Cambodia issued a decree banning the economic exploitation of Siamese rosewood a month before a Thai- and Vietnamese-led campaign saw the species added to the CITES treaty. But the trade has continued, led by former prime ministerial adviser Try Pheap, whose companies have allegedly made hundreds of millions of dollars in recent years by exporting protected timber species in breach of Cambodian laws, but with the tacit approval of Phnom Penh.

Jago Wadley, EIA’s senior forest campaigner, said he “was delighted to be given the opportunity to present to ASEAN member states on urgent policy responses to the illegal rosewood trade in the region”.

“The issues, and our proposals on them, were positively received and accepted by ASEAN CITES experts, and EIA looks forward to working with key ASEAN member states and wider parties to CITES in the coming months to progress formal proposals,” he said.