Maddox Jolie-Pitt, Angelina Jolie and Pax Jolie-Pitt arrive for the screening of "First They Killed My Father". Picture: AP

Angelina Jolie admitted she was "trying not to cry" as she dropped her first son off at college in South Korea on Wednesday.

Maddox Jolie-Pitt, 18, is attending Yonsei University in Seoul where he'll be studying bio chemistry.

The "Salt" actress and her teenage son spoke with some of Maddox's fellow students as they arrived on campus.

One Instagram user shared a video of Angelina on the social media app, in which she was asked how long she would be staying.

She said: "Only today. Today is the day I drop him off.

"I know, I'm trying not to cry."

Maddox has been preparing for his arrival in Yonsei by studying Korean.

A source said: "He got accepted to other universities but chose Yonsei. He has been studying Korean language. He has lessons multiple times a week to prepare."

Angelina - who adopted Maddox from an orphanage in Cambodia - helped him settle in before she headed back home to America.

The source added: "Mom is dropping him off in August. She is very proud. She will miss seeing him as much, but he's ready."

Maddox and Angelina first visited the university campus in November 2018 when his mother was on an official visit as the UN High Commissioner for Refugee (UNHCR) Special Envoy.

The 44-year-old actress - who was previously married to Brad Pitt - is also mother to Pax, 15, Zahara, 14, Shiloh, 13 and 11-year-old twins Knox and Vivienne.

Meanwhile, the "Girl, Interrupted" star recently gushed about how proud she is of her all of her sons and the "men they are becoming".

In an essay she penned for ELLE, she said: "I could not be prouder of my sons for the men they are becoming, the way they respect their sisters and are respected by them."