A photo posted by Diego Loyzaga (@diegoloyzaga) on Apr 16, 2015 at 10:43pm PDT

Diego Loyzaga puzzled many of his fans on Tuesday when he threw tact out the window and suddenly went after his father, actor Cesar Montano.

In a series of Instagram posts, the 21-year-old Loyzaga called Montano a liar and a hypocrite, and attacked his dad for rejecting him when he was young.

"Sa lahat ng nakakabasa nito, iisipin niyo siguro wala akong respeto kasi ama ko iyan. Pero sana tandaan niyo na mula ng pinanganak ako ng nanay ko eh dineny na ako niyan hangang ngayon! Kaya siguro puwede ako magsalita ng ganito," he wrote.

Loyzaga is Montano's son with former actress Teresa Loyzaga. He was raised in Australia by his mother but returned to the Philippines in 2011. He is currently an actor.

On his Instagram account, Loyzaga, appearing to have been provoked, unleashed several scathing posts against Montano whom he said has accused him of being drug addict.

"Padamputin mo na ako [at] lagyan ako ng karatula, 'di ba iyan ang sinabi mo?" he wrote.

Loyzaga added: "Kaming dalawa ng kapatid ko? Mag malinis ka na. Sakay ka na sa kanila pero sariling mong anak 'di mo ipagtatanggol. Sarili mo lang! Magaling. Best actor ka nga!"

Loyzaga then claimed that all five of the drug tests he took came out negative. "Pero [ang] lakas pa rin ng loob mo na pag bintangan akong adik."

Montano is a known supporter of President Rodrigo Duterte, who launched the country's war on drugs. He was recently appointed Department of Tourism Promotions Board chief operating officer and was seen getting friendly with Philippine National Police chief Ronald "Bato" dela Rosa in recent weeks.

In another pointed attack, Loyzaga lashed out at his father for what he described as one of his many broken promises.

He shared a photo of Montano saying that he paid for the tuition of his half-siblings, and wrote: "Salamat naman sa Diyos pinagaral mo ang mga anak mo. Karapat dapat lang naman ata ng isang ama gawin iyon, eh no?"

"Pangako mo sa akin? Nasaan na? Ayaw mo pa gawin to sa social media? Eh ako din ayaw ko sana pero puro ka hocus pocus. Daig mo pa magician. Wag ka nalang sana mag satsat kung 'di mo tutuparin."

Loyzaga punctuated his rant by saying that his account was not hacked as some of his fans were suggesting. "Ka tagal tagal ko ng na nanahimik tungkol dito pero kahit sinong tao napupuno din!"

ABS-CBN has reached out to Star Magic, the talent agency that handles the career of Loyzaga, for comment but the agency has not replied.

As of posting, the Instagram posts have been deleted.