Andrew Chan, Myuran Sukumaran and six others were executed on Wednesday by a firing squad on Nusakambangan prison island near Cilacap in Central Java.

Rose penned a lengthy note to Widodo - known for his love of hard rock and heavy metal - asking the President to intervene as a way of showing forgiveness and clemency in the face of international calls to halt the executions, while also requesting the same for convicted drug trafficker Mary Jane Fiesta Veloso.

"As all three are still alive," wrote Rose, "these are clearly not cases where nothing can or should be done by those who care to do their utmost in efforts to spare them. Under the circumstances it would seem that if they are executed regrettably the Indonesian government becomes the more offensive criminal.

"I appeal to you Mr. President, Mr. Joko Widodo to use your power in ways to strengthen international relationships between your country and others, to show your country's strength and allow the world to witness an extraordinary act of humanity and bravery on yours and your country's part."

"It's true I do not know these men nor have I met them but their story has touched me deeply," Rose continued. "I as well as many others could easily have found ourselves in their unfortunate and unarguably self-inflicted position. People make mistakes, sometimes big and horribly regrettable mistakes and sometimes more importantly people learn from their mistakes and make new choices, strive and succeed at true positive change. To not acknowledge and give such change the opportunity to prove its value would seem in this case a greater crime than those originally committed.

"I realize I am no one and no one to get involved with your affairs or those of your government and how this letter reads or anyone other than yourself thinks of it is irrelevant," said the singer. "Only the lives of these three human beings are what's important now.