Philippine Foreign Secretary Perfecto Yasay, a long-time friend of President Rodrigo Duterte, has been removed as the country's top diplomat.

The 15-member Commission on Appointments voted unanimously to boot him out yesterday, after it concluded that Mr Yasay lied that he was not granted US citizenship in 1986.

Mr Yasay said he did not lie, but that he may have "inadvertently misled" the commission.

In a previous hearing and in media interviews, he denied having a United States passport or having "legally applied" for American citizenship.

But in an interview aired on a cable news programme on Monday, he admitted that he "had an American passport".

"I did not lie. I may not have fully disclosed, but this is normal…

"You get nervous, you come up with answers you did not fully intend," he told the commission yesterday.

"I am a Filipino, and I am not an American citizen," he added.

However, Senator Panfilo Lacson, head of the Appointments Commission's Foreign Affairs Committee, said: "He was not telling the truth because he was not being forthright in the question-and-answer portion of the two hearings we conducted."

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 until June 28 last year. But he has insisted that in 1993, he issued an affidavit stating his US citizenship was "null and void" from the start, as he never had any intention of remaining in the US.

Shortly after issuing the affidavit, Mr Yasay was appointed associate commissioner of the SEC by fomer president Fidel Ramos.

Said Mr Yasay: "(It) was invalid under the US Immigration and Nationality Act because of a preconceived intent to relinquish my US residency at the time of the said grant, followed by the actual abandonment of such residency three months thereafter."

"Simply put," he added, "I did not lose my status as a Filipino for the reason that I did not validly acquire US citizenship."

He admitted appearing before a US consular officer on June 28 last year, but said it was to reaffirm his 1993 affidavit.

But Representative Josephine Sato, another member of the appointments body, said Mr Yasay could not renounce his US citizenship by simply issuing an affidavit. And his name was also not included in a US State Department list of immigrants who had lost US citizenship until Feb 9 this year, she added.

Mr Duterte appointed Mr Yasay, a college dorm mate, to head the Department of Foreign Affairs eight months ago, although he did not intend for him to stay on for a full six-year term.

Mr Duterte said he preferred Senator Alan Cayetano, who ran for vice-president but lost, as his foreign secretary. Mr Yasay was instead named as foreign secretary because the Philippine Constitution bars losing candidates from taking a government post within a year after an election.