MANILA -- Two former Philippine officials have filed a case against Chinese President Xi Jinping in the International Criminal Court in The Hague over the "massive" environmental destruction resulting from Beijing's land reclamation in the South China Sea.

The case, filed by former Foreign Affairs Secretary Albert del Rosario and Ombudsman Conchita Carpio Morales, was made public as President Rodrigo Duterte's top cabinet officials met their counterparts in Beijing this week, and touted improving bilateral relations.

In their letter to ICC Prosecutor Fatou Bensouda, Del Rosario and Morales urged the prosecutor to initiate a "preliminary examination" to "appraise itself of Chinese crimes committed not only against the Filipino people but also against people of other nations."

The complaint was filed on March 15, two days before Philippines officially quit from the ICC amid the court's examination over possible crimes against humanity committed in Duterte's brutal drug war.

The complainants, who said they represented hundreds of thousands of fishermen, alleged that Beijing's reclamation in the South China Sea is one of the "most massive, near permanent and devastating destruction of the environment in humanity's history."

China is not a member of the ICC, which raises questions over the court's jurisdiction.

China has converted at least seven underwater features into artificial islands with military infrastructure in order to bolster its claims in the South China Sea, which is rich in fisheries and energy resources and a pathway for $3 trillion to $5 trillion worth of global trade.

Del Rosario, an outspoken critic of China, was Philippines' foreign minister from 2011 to 2016 under the administration of former President Benigno Aquino. In 2013, he led a case against China at the Permanent Court of Arbitration in The Hague over the territorial dispute in the South China Sea, parts of which are also claimed by Brunei, Malaysia and Vietnam. Beijing did not participate in the case.

Manila won the arbitration in July 2016, but then newly elected leader Duterte set aside the issue to revitalize ties with Beijing, which has since pledged to fund his infrastructure initiative.

Both former maritime foes have also agreed to conduct joint resource exploration in the South China Sea.

Philippines' top officials, including incumbent Foreign Affairs Secretary Teodoro Locsin and Finance Secretary Carlos Dominguez were in Beijing this week for a series of meetings on maritime cooperation and infrastructure funding.