MANILA (UPDATE) - Sen. Bong Go on Monday questioned ABS-CBN Corp.'s decision to air a negative campaign advertisement against President Rodrigo Duterte in 2016, as a Senate panel tackled issues hounding the media company's license to operate.

In 2016, a negative political ad paid for by then-Sen. Antonio Triallanes was aired by ABS-CBN. It showed children reacting to some of Duterte's controversial remarks and expletives, including his cursing of Pope Francis and his comment about the rape-slay of an Australian missionary.

• Anti-Duterte ad causes uproar online

"Paano ito naging political ad? Ano ba ang priority ninyo? Black propaganda?" Go asked ABS-CBN officials present in the hearing.

"This is very troublesome. Media networks are supposed to be impartial... Kung nagawa ito sa isang kandidato sa pagka-presidente, paano pa sa isang ordinaryong mamamayan, ordinaryong Pilipino lamang?" he said.

The advertisement "maligned then-presidential candidate Duterte for the purpose of destroying his reputation" during a crucial period in the campaign for the presidency, said Go, Duterte's former aide.

A day after its first broadcast, the ad was pulled off air after then-Duterte running-mate Alan Peter Cayetano secured a temporary restraining order from a court in his bailiwick Taguig.

The court ruled that the ad "must be suppressed at once" as the repeated broadcast of "minors being used in black propaganda" would be "irreparably inimical to the children's welfare and interest."

The court also cited a Broadcast Code of 2007 provision which guarantees that "no program or sponsor shall be allowed to manifestly favor or oppose any candidate or political party."

Duterte's right to reply to the accusations against him "will be denied" because the advertisement was aired a few days before the 2016 presidential elections, it said.

• Cayetano gets TRO vs anti-Duterte ad

"Nasaktan ang presidente, nababoy ang presidente... Hindi vindictive ang pangulo but someone clearly went overboard with the airing of this black propaganda," Go said.

"Kung ganito na maaaring magsama-sama ang mga partido para pabagsakin ang isang tao... Tama po ang pangulo na labanan ang mga elistista at oligarkiya na naghahari sa ating bansa," Go said.

'NO POLITICAL AGENDA'

ABS-CBN president and Chief Executive Officer Carlo L. Katigbak apologized on behalf of the entire network, but belied allegations that the media company pushes its "own political agenda."

""We were sorry if we offended the President. That was not the intention of the network. We felt that we were just abiding by the laws and regulations that surround the airing of political ads," Katigbak told senators.

"Let me make a categorical statement that ABS has not and will not have its own political agenda," he said.

• TIMELINE: ABS-CBN franchise renewal