British pop singer Robbie Williams got candid while appearing on 60 Minutes Australia on Sunday, 25 February, about a bizarre UFO encounter that he had experienced.

In an interview titled The Extroverted Introvert, the 44-year-old star told Liam Bartlett, "I've seen a few strange things. I've experienced phenomena I can't explain."

Williams further went on to reveal that the incidents had occurred on multiple occasions when he was in America and in the UK as well, describing them as "intriguing and powerful".

The Angels hitmaker shared a detailed account of a UFO sighting he had experienced. "I've seen one right above me and if I got a tennis ball out I could have hit it with a tennis ball," he told Bartlett.

The journalist, who seemed shocked by the former Take That boy band member's confession, asked, "For the record, no substance was involved?" to which the Grammy winner confidently replied, "No substance was involved. No, no substance was involved at all."

Williams also opened up about the different sides to his personality in the candid interview. The Brit Awards winner admitted, "I'm an introvert, and I do an impression of an extrovert. My natural way of living would be sort of isolating away from people, and feeling uncomfortable in social situations."

The interview also touched upon the subject of George Michael death and he has asked, "Does that sort of thing makes you think of your mortality?"

Robbie said, "Yeah. Especially the things I have put myself through... But by the grace of God, I... it been so close so many times. Its been a very similar roller coaster and I miss George Michael and I wish he was here."

Williams, who rose to fame in the 1990s with boy band Take That, revealed that he struggles with self-doubt like any other person. "Fortunately or unfortunately, left to my own devices, I'm inclined to sabotage everything. I've got a disease that wants to kill me and it's in my head. So I have to guard against that."

The Angels singer was forced to cancel his final two tour dates in September 2017 after he was diagnosed with "abnormalities" in his brain. He has rushed him to hospital and spent seven days in intensive care.

He continued, "But most of the time, I am human, having a human experience. Trying to deal with the trials and tribulations of what goes on between my ears."

The 44-year-old is married to American actress Ayda Field and has two young children, 5-year-old Teddy and 3-year-old Charlie.