A US Air Force plane that may include House of Representatives Speaker Nancy Pelosi among its passengers entered the final leg of its journey to Taiwan after departing from Malaysia and taking an extended route that skirted the South China Sea.
Reuters could not immediately establish if Pelosi or her delegation were on flight SPAR19. Pelosi did not confirm if she was visiting the self-governed island, which Beijing claims as its own, but sources earlier told Reuters she was expected to arrive in Taiwan's capital Taipei later on Tuesday.
The plane left Malaysia's capital Kuala Lumpur at 3:42 p.m. (0742 GMT) on Tuesday and flew east toward Borneo on a route that skirted the South China Sea.
It was last seen north of the Philippines, according to Flightradar24, in the tracking site's most followed flight on Tuesday.
A visit to Taiwan by Pelosi, who is second in the line of succession to the US presidency and a long-time critic of China, would come amid worsening ties between Washington and Beijing.
She has not confirmed if she would visit the self-governed island which Beijing claims as its own.
Both the Philippines air force and its Department of Foreign Affairs (DFA) said they had received no word from the United States that Pelosi might land in the country on Tuesday.
"The DFA has not received any request from the US government or their embassy in Manila for Speaker Pelosi to transit and/ or visit the Philippines as part of her current swing of visits to the region," the DFA said in a text message to reporters.