MANILA, Philippines — The Philippine president on Monday called the sinking of a Filipino fishing boat that was hit by a Chinese vessel in the disputed South China Sea “a little maritime accident” and urged calm amid an outcry.

Twenty-two crewmen aboard the sunken boat were rescued by a Vietnamese fishing boat.

President Rodrigo Duterte said the June 9 incident at Reed Bank should not be blown out of proportion and should be investigated, and that China’s side should be heard.

Duterte's reaction contrasted with that of some of his own officials, including the defense chief, who strongly condemned the Chinese vessel for sailing away as the fishing boat sank at night. The Department of Foreign Affairs filed a diplomatic protest against China.

Duterte came under fire from nationalists and opposition politicians for his silence days after the incident was made public by Defense Secretary Delfin Lorenzana.

One opposition senator called on the president to downgrade diplomatic ties with China, which has been criticized for aggressive actions in the disputed waters.

"It's just a collision of ships, do not make it worse," Duterte said in his first public remarks about the incident, adding he would not reach any conclusion or take any action until an investigation is complete.

"Let's not get involved yet," he told officials and personnel at a naval base in Cavite province, south of Manila, during the anniversary of the Philippine navy.

He warned that the “little maritime accident” could degenerate into a bigger conflict at a time when the Philippine military is still trying to modernize.

Normally known for his temper and spontaneous outbursts, Duterte this time underscored the importance of handling the incident by the rule of law. He said politicians who urged him to deploy the navy in response to the incident were “stupid,” although he did not identify any.

China has acknowledged its fishing vessel hit a Filipino boat in the vicinity of Reed Bank but denied the collision was intentional.

The Chinese Embassy in Manila said Friday that the Chinese vessel accidentally hit the Philippine boat as it tried to maneuver while surrounded by several other Philippine boats.

It said the Chinese captain tried to rescue the Filipinos but was afraid of being besieged by the other boats.

The Filipino fishermen denied China's claims and said they would have died if they had not been rescued by the Vietnamese boat.

Reporters interview a crew of Filipino fishing vessel F/B Gimver 1, Richard Blaza, center, during a press conference at the Department of Agriculture in metropolitan Manila, Philippines on Monday. (Aaron Favila/AP)
Reporters interview a crew of Filipino fishing vessel F/B Gimver 1, Richard Blaza, center, during a press conference at the Department of Agriculture in metropolitan Manila, Philippines on Monday. (Aaron Favila/AP)

It was one of the most serious recent incidents in the disputed waters involving fishermen from the Philippines and China, whose ties have improved under Duterte.

The Philippine leader moved to repair frayed relations as he sought Chinese infrastructure funds and trade and investment after taking office in 2016.

The territorial conflicts, which also involve Vietnam, Malaysia, Taiwan and Brunei, have long been seen as a potential flashpoint.