MANILA (Reuters) - Philippine President Rodrigo Duterte said on Friday (Feb 24) he was not sure why China's commerce minister had cancelled a trip to his country, and that Beijing misunderstood his foreign minister's comments about its militarisation in the South China Sea.

In a speech in which he expressed his intention to have solid ties with China, Duterte said there was no need to press it to abide by an international arbitration ruling last year.

Foreign Secretary Perfecto Yasay, as chair of the Asean foreign ministers' meeting, said on Tuesday said the region had"grave concerns" about Chinese weapons installations on manmade islands in the South China Sea.

"The problem is I think Secretary Yasay was misunderstood by the Chinese government," Duterte said in a speech. "I would like to assure China, and this is what I had committed to do when I was there, that we will talk as friends," he said, referring to a trip he made to China last year.

China's Commerce Minister Gao Hucheng decided at the last minute to postpone an official trip on Thursday to the Philippines to sign about 40 joint projects worth billions of dollars. No reason was given by either side.

Establishing better relations with China has been a key plank of Duterte's sometimes perplexing foreign policy, which has seen him lash out at major donors and investors such as the United States and European Union.

He is keen to tap China for loans, tourists and infrastructure.

On Friday Duterte said the Philippines' longstanding alliance with the United States did not make it "duty bound to follow" Washington's foreign policy, and conflict with Beijing was not an option.

"We cannot go to war because we cannot afford it," he said."And as much as possible, the bilateral relations between the two countries would be enhanced and improved and trade and commerce between the two countries greatly improved."

But that could be affected by Yasay's comments that Asean members were "unanimous in their expression of concern" about"very unsettling" developments. He mentioned China by name, something the 10-nation grouping is often reluctant to do.

China's foreign ministry spokesman, Geng Shuang, on Thursday told a regular briefing that Yasay's remarks were "baffling and regrettable", and he hoped Yasay would "speak and act cautiously".