MANILA, April 2 (Xinhua) -- The Electoral Tribunal in the Philippines officially began on Monday a manual recount of votes cast in the disputed vice-presidential ballot.

The recount was requested by the former Senator Ferdinand Marcos Jr., the son of ousted President Ferdinand Marcos.

Marcos Jr., who lost to incumbent Leni Robredo by about 260,000 votes, contested the outcome of the vice-presidential election in May 2016, claiming it was marred by "massive cheating."

The ballots, which were counted by machine, will be tallied again manually by the Supreme Court, sitting as the Presidential Electoral Tribunal (PET).

PET spokesperson Theodore Te said the recount of votes covers 5,418 precincts in three provinces which were selected by Marcos Jr., namely Province Camarines Sur, Province Iloilo, and Province Negros Oriental.

Te said the recount is being done to "ascertain the number of votes received by both parties in the May 9, 2016 national elections throughout a manual recount of the votes."

During the revision, Te said "the Head Revisor will segregate and examine the contents of each ballot box and on the basis thereof, determine the number of votes received by each party."

In June 2016, Marcos Jr. filed the electoral protest and accused Robredo of cheating in the May 2016 elections. Marcos expectedly urged the PET to declare him as the elected and rightful vice president of the country.

Robredo had also lodged a counter-protest at the PET, questioning results in about 8,000 voting precincts.

A few hours into the counting, Marcos Jr. told reporters that some of the ballots from Camarines Sur, Robredo's hometown, were doused, making them "illegible".

Robredo's lawyer Romulo Macalintal slammed the allegation of Marcos Jr.

"The statement of Mr. Marcos about the alleged anomaly is fake news, false," Macalintal said.

Robredo told his supporters that there's nothing to be concerned about.