Julian Lennon performed his late father John Lennon's song Imagine for the first time ever on Saturday.

Taking to Instagram on Saturday, the singer-songwriter posted a video of him performing the 1971 hit in a dark room surrounded by candles and accompanied by acoustic guitarist Nuno Bettencourt.

In the accompanying caption, Julian explained that in delivering his take on Imagine, he broke a vow that he would only perform the song "if it was the End of the World".

He posted the video during a benefit for Ukrainian refugees, closing out a televised European Union pledge drive that raised $10.1 billion in grants and loans for the cause.

"Today, for the first time ever, I publicly performed my Dad's song, Imagine," the 59-year-old wrote. "I had always said that the only time I would ever consider singing Imagine would be if it was the End of the World...

"The war on Ukraine is an unimaginable tragedy... As a human, and as an artist, I felt compelled to respond in the most significant way I could."

Of the track, Julian continued: "Within this song, we're transported to a space, where love and togetherness become our reality, if but for a moment in time...The song reflects the light at the end of the tunnel, that we are all hoping for."

The drive, called Stand Up for Ukraine, ended on 9 April, but humanitarian organisations are still taking donations.