By Yew Lun Tian and Karen Lema

(Reuters) -China's foreign minister Qin Gang will not attend a diplomatic gathering in Indonesia as expected this week, sources familiar with the matter said, extending an unexplained public absence that has lasted for more than two weeks.

Three sources familiar with matter, who declined to be identified because they are not authorised to speak to media, said top diplomat Wang Yi would represent China at the meetings in Jakarta instead.

Foreign ministers of the Association of Southeast Asian Nations (ASEAN) and China are scheduled to meet on Thursday, before Friday's East Asia Summit and ASEAN Regional Forum.

Qin, 57, took over from Wang as foreign minister in December and was last seen in public on June 25 in Beijing after meeting officials from Sri Lanka, Russia and Vietnam.

The Chinese foreign ministry did not respond to a query about Qin's whereabouts.

His absence has not gone unnoticed.

Foreign ministry spokesperson Wang Wenbin was asked last Friday about an article in U.S. political news website POLITICO that cited speculation that health issues may be behind Qin's absence. He said he had "not heard about" the report.

Qin was supposed to meet European Union foreign policy chief Josep Borrell last week in Beijing but the meeting was pushed back after China informed the EU that the dates were "no longer possible", an EU spokesperson said.

The EU was informed of the postponement just two days before Borrell's scheduled arrival on July 5, according to a source familiar with the plans.

Wang Yi, who is the foreign policy chief for the Chinese Communist Party, ranks above Qin, who as the foreign minister is the government's foreign policy chief.

(Reporting by Yew Lun Tian in Beijing, Karen Lema in Manila and Stanley Widianto in Jakarta; Writing by Martin Petty and John Geddie; Editing by Robert Birsel)