Ten foot waves, strong winds and toxic fumes from the burning oil have been hindering efforts to extinguish the fire.
The Iranian tanker, Sanchi, has been ablaze since it collided with Hong-Kong registered freight ship CF Crystal on Saturday night, 185 miles off China's coast near Shanghai.
Sanchi was carrying almost one million barrels of highly flammable crude oil to South Korea with 32 crew members on board - 30 Iranians and two Bangladeshis.
All are missing, but the body of a mariner suspected to be from the ship was recovered on Monday.
The 21 Chinese crew members on the CF Crystal, carrying grain from the US, were rescued.
Amid fears the tanker could break up and sink, dozens of rescue boats have doused the vessel with foam.
However, they were forced away on Wednesday due to an explosion on the Sanchi.
Ten foot waves and strong winds, along with toxic fumes from the burning oil, have also been hindering the efforts to extinguish the fire.
The tanker has also now drifted away from the Chinese coast and into Japan's exclusive economic zone (EEZ), Japan's coast guard said.
The vessel was 286 km (178 miles) northwest of Sokkozaki at 7am on Friday.