Beijing and Manila have traded barbs over a Chinese research vessel near a disputed South China Sea reef, with each warning of further countermeasures, a sign of lingering tensions between the two rival claimants.

In a statement issued on Thursday night, China Coast Guard (CCG) spokesman Jiang Lue said a Philippine Coast Guard Islander aircraft had “deliberately approached and harassed” China’s Xiang Yang Hong 33 scientific research vessel on Wednesday while the ship was conducting a “legitimate marine ecological survey” near Iroquois Reef.

Claimed by China as Houteng Reef and known as Rozul Reef in the Philippines, the feature is at the southern end of Reed Bank in the contested Spratly Islands, an area believed to be rich in oil and natural gas.

Jiang said the Chinese side tracked and monitored the Philippine aircraft and handled the situation “in accordance with laws and regulations”, with manoeuvres that were “professional and standardised throughout the whole process”.

“We sternly warn the Philippine side to immediately stop illegal harassment, smearing and inflammatory propaganda,” he said.

Jiang’s comment came hours after his Philippine counterpart Jay Tarriela issued a release on social media, stating that on Wednesday the Philippines had sent an Islander 4177 surveillance aircraft for a routine maritime domain awareness mission – designed to detect, track and identify vessels and activities at sea – “specifically” challenging China’s Xiang Yang Hong 33.

Tarriela accused the Chinese oceanographic research vessel of taking “unauthorised” marine scientific research operations.

He said the Philippine Islander plane on Wednesday monitored one Chinese Coast Guard vessel in the western part of Iroquois and 13 Chinese maritime militia vessels anchored in the surrounding waters.