Vietnam’s coast guard has seized a Chinese fuel ship for allegedly intruding in its waters amid the ongoing territorial dispute in the South China Sea, state media reported Monday. The vessel was reportedly intercepted in waters near the Vietnamese island of Bach Long Vi and the Chinese island of Hainan last Thursday.

The ship, which had been disguised as a fishing boat, was carrying more than 100,000 liters of fuel, BBC reported, citing the government-owned Vietnam News Agency. Local media reports said that the captain and two crew members have been arrested by Vietnamese officials.

The captain of the seized vessel told authorities that the fuel was to be sold to Chinese fishing boats operating in the area, the Associated Press reported, citing local media Thanh Nien.

Local media reports claimed that Vietnam’s coast guard had chased 110 Chinese fishing boats out of Vietnamese waters last month. Vietnamese fishermen have often complained about harassment of its own fishing boats by Chinese authorities.

Tensions between China and Vietnam erupted over Beijing’s claim over most of the South China Sea. The relations got strained since China parked an oil rig in waters off the Vietnamese coast in 2014. The incident sparked anti-China riots in Vietnam that left five people dead. Hundreds of factories owned by Chinese and other foreign companies were looted and burned during the riots.

In January, Vietnam expressed concerns over China's moving of an oil rig in the disputed South China Sea that could potentially result in a repetition of the 2014 standoff. The same month, Vietnam accused China of violating its sovereignty by landing a plane on the disputed Spratly Islands.

The South China Sea region, through which about $5 trillion in ship-borne trade passes every year, has been long disputed, with Brunei, China, Malaysia, the Philippines, Taiwan and Vietnam laying claim to various areas.