MANILA (Reuters) - The Philippines expressed “serious concerns” over the presence of China’s strategic bombers in the disputed South China Sea and its foreign ministry has taken “appropriate diplomatic action”, the spokesman of President Rodrigo Duterte said on Monday.

FILE PHOTO: Philippines President Rodrigo Duterte gestures during an armed forces change of command ceremony at Camp Aguinaldo in Quezon City, Metro Manila, Philippines April 18, 2018. REUTERS/Dondi Tawatao/File Photo

China’s air force said bombers such as the H-6K had landed and taken off from islands and reefs in the South China Sea as part of training exercises last week, drawing angry reactions from opposition lawmakers in Manila. The United States also sent ships to the disputed areas.

The Philippines could not independently verify the presence of Chinese bombers in the South China Sea, said presidential spokesman Harry Roque.

“But we take note of the reports that appeared and we express our serious concerns anew on its impact to efforts to maintain peace and stability in the region,” Roque told a regular media briefing at the presidential palace.

The Department of Foreign Affairs in the Philippines said it was monitoring developments.

“We are taking the appropriate diplomatic action necessary to protect our claims and will continue to do so in the future,” it said in a statement, but it did not elaborate.

However, the foreign ministry stopped short of condemning China’s action, which Washington said could raise tension and destabilize the region.

In Beijing, a foreign ministry spokesman urged other countries not to over-interpret what he called a routine military patrol.

“We hope that relevant parties do not read too much into this,” Lu Kang told a daily news briefing.

China claims almost the entire South China Sea, a strategic waterway through which about $3 trillion worth of sea-borne goods pass every year. Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have conflicting claims in the area.

China has built seven artificial islands in the Spratlys group in the South China Sea and turned them into military outposts with airfields, radars, and missile defenses.

Beijing says its military facilities in the Spratlys are purely defensive and it can do what it likes on its own territory.

Roque and foreign ministry officials said Manila would raise China’s moves to militarize its manmade islands in the Spratlys during two-way consultations in China set for the second half of the year.

Lawmakers in the Philippines have criticized Duterte for setting aside an arbitration ruling by the Hague the country won in 2016. Former foreign minister Albert del Rosario has urged Duterte to “revisit” the country’s foreign policy.

“We are opposed to war - as we should be. But if threatened by the use of force, we should be ready to inflict, at the very least, a bloody nose on any attacker who is out to harm us,” Del Rosario said in a statement.

Duterte has said he would not risk a confrontation with China and has reiterated his openness to joint exploration and development in waters believed to be rich in oil and natural gas.