MANILA (UPDATED) - Former Securities and Exchange Commission chair Perfecto Yasay Jr. has accepted the offer of presumptive president Rodrigo Duterte to be acting foreign affairs secretary.

Yasay, 69, a lawyer, was SEC chair under former President Joseph Estrada. President Fidel Ramos appointed him SEC associate commissioner in 1993 and was chairman from 1995 to 2000.

"I was astounded and humbled by the offer. This is an opportunity for me to really serve the country and I am happy to learn that the presumptive president has put his trust to me and the important thing is I would try to live up to the trust and the challenge," he said in a phone interview on ANC.

Yasay will be acting secretary of the Department of Foreign Affairs (DFA) for one year or until the post is turned over to Senator Alan Peter Cayetano.

LOOK: Duterte's Cabinet and then some

Yasay said he will carry out his job faithfully and diligently whether or not Duterte chooses to extend his term.

He said he hopes that "in carrying out my duties as foreign affairs secretary, I would be able to assist the president in carrying out our paramount national interests."

"I am not at all bothered by the fact that he has indicated appointing me an acting capacity for a year because I really know, having been in government before, that whether or not you're fixed term or your appointment is permanent, you really serve at the pleasure of the president," he said.

Cayetano, Duterte's running mate in the 2016 elections, was initially offered the post.

However, Cayetano, who lost in the vice-presidential elections, will have to wait for one year before he can be appointed to the post.

Cayetano has three years left in the Senate. Yasay said Cayetano was eyeing the Senate presidency.

Duterte earlier said he and Yasay were roommates when he was studying law in San Beda College. Yasay was then taking up law in the University of the Philippines.

For Yasay, he said that one of the most telling moments that they had during those days was when martial law was declared.

"We thought that the struggle to make sure that freedom is restored would be realized and we had our dreams to somehow participate in the shaping of our destiny. We were, in the real sense, the youth leaders then being molded into the leadership of the country and the future. In this sense, now that he's president, I feel that somehow his dreams have been fulfilled," he said.

Yasay, like Duterte, has roots in Mindanao. He was born in Kidapawan, Cotabato. He finished his secondary education in Davao City High School.

Aside from the West Philippine Sea, Yasay said the incoming Duterte administration would like to give priority focus, for example, to the plight of overseas Filipino workers as well as the environment.

He said the Duterte administration would "work to the hilt to make sure that concerns are addressed."

Also, the new administration is likewise very much concerned with steps to counter violent extremism.

"This is something that you can be sure that this incoming administration will also focus on," he said.

As to the offer to welcome back Communist Party of the Philippines founder Jose Ma. Sison, Yasay said: "I think the offer of presumptive president to welcome Joma Sison to come back is clearly conditioned on the fact that when they come back, they lay down their arms."

He added that it would not be a good policy to talk peace with them and allow them to continue to hold on to their arms and fight government.

"I would see that the offer of our presumptive president in forging a closer relationship with these rebels in giving them amnesty on condition that they lay down their arms as precondition to talking peace," he said.

Yasay was the running mate of evangelist Bro. Eddie Villanueva in the 2010 elections. They were the candidates of Bangon Pilipinas party and they both lost.

READ: Bangon Pilipinas' Yasay concedes

In 2001, Yasay ran for a seat in the Senate under Senator Raul Roco's party, Aksyon Demokratiko, but also lost.

Yasay was thrust into the national scene when, as SEC chair, he told a Senate committee that then-President Joseph Estrada pressured him to back off from the investigation into the Best World (BW) Resources insider trading scam.

According to Yasay, Estrada wanted him to clear his friend, BW majority owner Dante Tan.

Yasay will take over from Foreign Affairs Secretary Jose Almendras. -- report from Dexter Ganibe, DZMM/ABS-CBN News and ANC