MANILA - President Rodrigo Duterte warned of trouble if China will unilaterally exploit resources in the disputed South China Sea.

Duterte has been recently changing tune about the bitter maritime dispute, as he slammed China for its “nasty” warnings to Filipino pilots conducting patrols over the Spratly Islands.

• Duterte hits China's 'nasty words' to patrolling PH pilots

In a speech in Cebu City Tuesday, Duterte said in jest he would send Interior department head Eduardo Año, a former military chief, to attack the Chinese if they will exploit resources in South China Sea without the Philippines’ permission.

“Eh kung solohin mo, gulo talaga ‘yan. Because if you struck oil now, ano ba naman ‘yang dagat? Hayaan na. Sayo na lahat, kunin mo lahat,” Duterte said in a mix of Filipino and Bisaya.

“Pero p***** i** ‘yung mga uranium diyan, ‘yung mga… Ah mahirap ‘yan. Iyong oil, mahirap ‘yan. Diyan magkadiperensiya na tayo, diyan mo na makita si Año magdala ng sundang (bolo) didto sa ---- panigbason (pagtatagain) ang mga Intsik."

China claims sovereignty to almost the entire South China Sea, and has caused concerns that it will deprive the Philippines of its rights to exploit resources in the sea.

The Philippines and China are now in talks for a possible joint development in the South China Sea.

In May last year, Duterte said he insisted to Chinese President Xi Jinping that the Philippines will drill oil in the sea. He said this prompted Xi to warn of war.

• Duterte: China warned PH of war over South China Sea

National Security Adviser Hermogenes Esperon had also said that the Philippines could go to war with China if Filipino troops patrolling the sea are attacked.

Since assuming the presidency, Duterte has sought to downplay Manila’s maritime dispute with Beijing in exchange for improved ties with the world’s second-largest economy.

Duterte has also refused to flaunt the Philippines’ victory against China in a United Nations-backed arbitration court in 2016 which invalidated Beijing’s expansive claims to the waters.

In an interview with CNN in December 2016, however, Duterte said he would bring up the ruling “when the minerals are already being siphoned out.”

“Wait a minute, I thought we're friends. We share economic bounties and…So how about us? I have this title,” Duterte said then.

Duterte’s predecessor, former President Benigno Aquino III, initiated the case against China but the ruling was handed down less than a month after the incumbent assumed power.

Duterte and Foreign Affairs Secretary Alan Peter Cayetano have drawn criticism for Manila’s policy towards China. The top diplomat has, however, said the Philippines has been quietly taking diplomatic actions against Chinese incursions in the disputed waters.