Thailand Restricts Fuel Runs to Cambodia with Tough AIS and Permit Rules

Thailand’s coastal security framework has entered a new phase: any ship flying the Thai flag yet masking its identity while hauling fuel to Cambodia now risks detention, heavy fines and possible port bans. Increased coordination among maritime, customs and military agencies underscores Bangkok’s resolve to stamp out illicit oil runs and safeguard national interests.

Key developments at a glance

• Expanded surveillance along 23 coastal provinces, from Trat to Satun, with drone and radar patrols covering river mouths and offshore transfer spots.

• Mandatory AIS transparency: vessels must broadcast continuous positioning for the last 72 hours or face automatic berth holds.

• Interagency task force uniting the กรมเจ้าท่า Marine Department, Customs, Royal Thai Navy, Excise and Fisheries to oversee energy and dual‐use cargoes.

• Port‐state controls tightened: Cambodian‐flag tankers breaching Thai laws can be refused entry, and false‐flag operators silently reflagged on the spot.

• Enforcement uptick in 2025 saw multiple trawlers converted into illicit tankers intercepted, cutting suspected smuggling voyages by over 30% since mid‐year.

A multi‐layered approach to maritime oversight

Bangkok’s National Security Council has laid out four interlocking measures to clamp down on disguised or falsified vessel registrations. First, real‐time integration of radar, satellite and AIS data now feeds into a 24/7 fusion hub. Drones monitor known offloading points in mangrove creeks and river mouths, while patrol boats inspect ships near the 12‐nautical‐mile limit.

Second, enforcement hinges on cross‐agency cooperation. The ศูนย์อำนวยการรักษาผลประโยชน์ของชาติทางทะเล (ศรชล.) leads joint inspections with the Customs Department and Excise, ensuring that any tanker leaving Thai ports with petroleum presents a valid export permit, pollution prevention certificate and a digital voyage log.

Third, any vessel—Thai or foreign—found loading or offloading fuel in violation of innocent passage rights under UNCLOS or port‐state regulations may be barred from Thai harbors. This sends a clear message that false‐flag operations will trigger both criminal proceedings and retroactive tax claims.

Finally, safety protocols aim to protect legitimate mariners. Clear corridors for authorised cargo flows are marked, and operators are urged to report suspicious activities immediately to local maritime authorities.

Behind the stats: 2023–2025 enforcement highlights

Officials say the stepped‐up campaign is already yielding results:

• In 2023, 7 major seizures netted over 600,000 L of untaxed diesel, with 41 crew members prosecuted.• The following year, Thai excise coffers saw an 80 B ฿ boost after more than 1,000 oil‐smuggling cases.• In 2025, December raids in Satun uncovered two converted trawlers carrying 8,000 L of marine gas oil, plus fines exceeding ฿660,000.

Overall, attempted smuggling voyages have fallen by roughly 35% since the new protocols took effect in mid‐2025.

What shipowners must do now

Commercial tanker operators should prepare for heightened scrutiny:

File departure notices 48 hours in advance via the Marine Department portal.

Maintain uninterrupted AIS broadcasts; any signal loss over 20 minutes raises immediate red flags.

Carry certified fuel‐quantity seals and logs covering the previous three days.

Store six months of communications records with brokers to counter forgery allegations.

Ensure all crew are registered in the Thai Seafarer e‐database to speed inspections.

Failure to comply can result in vessel detention, reflagging by the Navy—nullifying insurance—and fines that climb into the millions of baht.

Regional tensions and legal dynamics

Cambodia has lodged diplomatic protests, accusing Thailand of imposing an economic blockade by restricting port access. AmCham Cambodia warns of serious implications for US‐linked businesses. Yet Thai legal scholars point out that Phnom Penh’s non‐ratification of UNCLOS gives Bangkok broader latitude to police its territorial waters; overlapping claims over some 26,000 sq km in the Gulf remain unresolved.

Rear Admiral Jumbol Nakbua, Thai‐MECC spokesman, insists the measures target only vessels flying the Thai flag or foreign ships inside Thai waters, in line with international law. Meanwhile, experts such as Dr Thon Thamrongnawasawat of Kasetsart University stress that any push to close the Gulf entirely would invite WTO challenges.

Looking ahead: cleaner lanes, higher costs

For legitimate exporters serving Cambodia’s factories and power plants, the new framework means more paperwork and onboard checks but also a fairer market free of cut‐price, tax‐dodging rivals. Thai consumers may see slight adjustments in fuel prices as companies factor in compliance costs. Yet officials argue that securing revenue and denying illicit operators their profits ultimately benefits the Thai economy and strengthens regional stability.

As Bangkok fine‐tunes its maritime defenses, the message is unmistakable: masking your identity at sea is no longer worth the risk. Clear compliance will keep trade routes open—and the coastguard vigilant.