MANILA - Philippine Foreign Secretary Perfecto Yasay, a longtime friend of President Rodrigo Duterte and a former securities regulator, has been booted out.

In a unanimous vote, the 15-member Commission on Appointments, consisting of legislators, voted on Wednesday (March 8) to reject Mr Yasay's appointment. The commission determined that Mr Yasay had lied when he failed to declare his US citizenship and was therefore not qualified to serve as Cabinet secretary.

Mr Duterte appointed Mr Yasay, a college dorm mate, to head the Department of Foreign Affairs temporarily.

He said soon after he took office in June that he preferred to appoint Senator Alan Cayetano, who ran with him as his candidate for vice-president but lost to Liberal Party candidate Leni Robredo, as foreign secretary.

The Philippine Constitution bars losing election candidates from holding government posts for a year after the election.

Recently, however, Mr Yasay had insisted on staying on, saying Mr Duterte had not officially told him his tenure was for only a year.

Mr Duterte has stayed mum on this issue.

Mr Yasay also argued that it would "look bad" for the Philippines to replace its foreign secretary when it is acting as chair of Asean.

During his confirmation hearing on Wednesday, he claimed plans to remove him as foreign secretary is part of a plot to destabilise Mr Duterte's government.

Mr Yasay, a lawyer and former head of the Securities and Exchange Commission (SEC), has been dogged by allegations that he took up US citizenship in 1986, and failed to renounce it till June 28, 2016.

Mr Yasay explained that the form he filed in 2016 merely reaffirmed an affidavit he issued in 1993 declaring that the US citizenship he obtained in 1986 was "null and void" because he had all along no intention to remain in the United States.

But he was forced to admit to holding a US passport, which he twice denied, including at a hearing of the Commission on Appointments.

Representative Josephine Sato, a member of the commission, said Mr Yasay cannot renounce his US citizenship by simply issuing an affidavit.

Mr Yasay was head of the SEC in 2000 when he linked his boss, then President Joseph Estrada, to a huge stock market scandal ran by a business crony. His testimony helped build a case that led to Mr Estrada's impeachment and ouster in 2001.