MANILA -- Senate President Vicente "Tito" Sotto III said Monday he believed President Rodrigo Duterte fired Vice President Leni Robredo as co-chairperson of an anti-drug body due to loss of trust.

Likening the President to a basketball coach, Sotto, also a vocal anti-drug advocate, said the chief executive had the prerogative on "who to put in and who to pull out."

"The appointment of the Vice President as ICAD co-chair is based on trust. Once trust is lost, the position is lost. We have a word for it in Filipino - Sayang," Sotto said.

Sotto was referring to the Inter-Agency Committee on Anti-illegal Drugs, which Robredo co-chaired for 2 weeks, taking up the President's dare for her to lead the government's anti-drug campaign.

• 'I don't trust her': Duterte says no need for Robredo to get classified information

"He wanted her to see the extent of the drug problem up close. I'm sure he trusted her then but when he probably felt the job description was not being followed, he had a different opinion," Sotto said.

Duterte's spokesman Salvador Panelo on Sunday said Robredo failed to present a plan on how to solve the country's illegal drug woes, adding, "Meron na siyang pagkakataon, she blew it (She had a chance but she blew it.)"

• Robredo used drug war for 'grandstanding,' says Duterte spox

Robredo accepted Duterte's offer to co-chair the ICAD, saying it would give her a chance to prevent unnecessary deaths under the drug war.

-report from Sherrie Ann Torres, ABS-CBN News