Gerard Butler has been left "devastated" following the death of his "dear friend" Darius Campbell Danesh.

Gerard Butler pays tribute to his 'brother in arms' Darius Campbell Danesh

Gerard Butler pays tribute to his 'brother in arms' Darius Campbell Danesh

The '300' star took to Instagram to share a lengthy tribute to his "brother in arms", who died aged 41 after was found unresponsive in his apartment in Rochester, Minnesota, on August 11.

Gerard - who was pictured hanging out with his fellow Scot in Malibu in June - wrote: "I am devastated by the sudden passing of my dear friend Darius, a true brother in arms. My thoughts and love go to his wonderful mum and dad Avril and Booth and his two brilliant brothers Aria and Cyrus.

To those lucky enough to have met Darius for more than a few minutes, they were deeply moved by his infectious laugh and barely containable zest for life. He was always armed with a smile, a booming voice, and a genuinely warm embrace that few could resist-nor would they want to!!! He was an incredible talent, a singer whose voice touched your soul and an actor with great presence. But, most importantly, he had the heart of a lion. It was bigger and brighter than the sun and an energy so contagious he could light up a room in seconds.

"Our boy Darius was always constant and unwavering in his passion for life. But a bigger constant was his dream to inspire others to better themselves. He talked the talk but boy, did he walk the walk. He had such purity of thought, a deep wisdom and constant gratitude for people, for life, a compassion towards all. His hilarious self-deprecating sense of humor (he was funny as shit) allowed him to stay humble - something he valued deeply. Darius’ undying commitment to being of service to individuals- his family, his friends (none more so than me) and to the world at large made him the perfect friend- He led by example but he was also a teacher, as he pushed those he loved to be the best possible versions of themselves. (sic)"

Gerard admits his heart "aches heavily" following his pal's passing, but he hopes there will be a "meaning" as to why Darius departed "so early".

He added: "The universe unfolds in ways we may not agree with or even understand. Somewhere in there I believe there is, or will be, some meaning in why he left us so early. If it was nothing more than teaching us to live with that open heart, putting others first and never taking ourselves too seriously as we learn to traverse this wonky world we live in then, that might be enough. But something tells me there will be way more waves created by our boy Darius further down the line. My heart aches heavily. But going forward, I will beat my drum louder and celebrate life and its every beautiful moment because my brother showed me that was a pretty awesome way to go about it. (sic)

Gerard's tributes come after Simon Cowell paid tribute to the "charismatic" star.

The music mogul was wowed by the singer on 'Pop Idol' in 2001 and offered him a record deal after he finished third on the show.

Simon said in a statement: "I first saw Darius on television over 20 years ago and I got to know him really well.

"He was charismatic, funny and just a great person to be with.

"His passing, for someone so young, is an absolute tragedy and my heart goes out to his family and friends."

Darius turned down Simon's deal and signed on with U2 producer Steve Lillywhite instead.

Despite rejecting the chance to team up with the 'X Factor' boss, Darius later described Simon as a "friend".

Will Young won 'Pop Idol' in 2001, with Gareth Gates finishing second.

Gareth has also paid tribute to the late star, admitting he has been left "heartbroken" over his pal's passing, and admitted Darius was like a "big brother" to him on the talent show.

He said in a statement: "I can’t quite believe the news of my dear friend Darius passing. I’m heartbroken.

"Darius took me under his wing during our time in 'Pop Idol', like a big brother; always looking out for me and for that I thank you my friend."

Darius' family confirmed this week that he had sadly passed away.

They said in a statement: "It is with great sadness that we announce the passing of Darius Campbell Danesh. Darius was found unresponsive in bed in his apartment room in Rochester, Minnesota, on August 11 and was pronounced dead in the afternoon by the local medical examiners' office."