An expected visit to China by a special envoy from the Philippines will offer direct channels for improving icy ties between the countries, but neither side should harbor hopes of an instant breakthrough, experts said on Thursday.

New Philippine President Rodrigo Duterte said on Wednesday that former president Fidel Ramos will visit China as a special envoy. He did not give a date for the trip.

Ramos, 88, served as Philippine president from 1992 to 1998 and has maintained good personal ties with China.

The Philippine Star newspaper quoted Duterte on Thursday as saying Ramos' trip is not part of the official negotiations on South China Sea disputes, and Ramos will not be meeting with Chinese officials but with "friends".

Ties between the two countries became deadlocked in 2013 after the previous Philippine government led by Benigno Aquino sought third-party compulsory arbitral proceedings against China.

Last month, an arbitral tribunal in The Hague issued a ruling in Manila's favor. Beijing has urged the Duterte administration to put aside this ruling before resuming political dialogue and negotiations.

Duterte said on Wednesday that when the time comes for negotiations, the Philippines will not stray from the arbitral award.

Zhang Jie, a researcher of Asia-Pacific studies at the Chinese Academy of Social Sciences, said it is unlikely that Manila will completely put aside the arbitral ruling as this gives it an effective tool or bargaining chip.

"China has political needs, while the Philippines has economic needs. Both countries should show flexibility to enable dialogue and negotiation," Zhang said.

"Such a resumption should start with unofficial, lower-level contacts before proceeding to negotiations requiring multiple rounds. So we should not have too great an expectation at first," she added.

Teng Jianqun, a researcher of US studies at the China Institute of International Studies, said China's recent responses have left plenty of room for the Philippine Cabinet to rebuild contacts.