The veteran singer, who had been battling ill health in recent months, passed away on Wednesday (06Apr16).

The news emerges days after Haggard cancelled all scheduled shows for April (16), as his doctors had ordered him to rest up following his hospitalisation in January (16), when his bout of double pneumonia returned. He had previously been hospitalised for the same ailment in December (15).

Haggard had reportedly been receiving treatment in hospice care in his final days, according to CountryAircheck.com.

Announcing his latest concert cancellations on 29 March (16), the Okie From Muskogee singer admitted he was saddened to scrap the live dates.

"I want to thank my fans for their prayers and well wishes," he said in a statement via his publicist. "I hope to be back on the road in May, but I'm taking it one day at a time."

He had previously told Rolling Stone magazine he was on the mend, after he "nearly died" in December (15), when he spent 11 days in hospital.

"I'm really lucky to be alive," he told the publication. "It could've gone in another direction had I messed around a little more. I'm just hoping I'm fully able... It was like suffocating, like having a pillow in your face. It's a terrible thing; people die from it all the time."

He added, "I'm doing a lot of writing and I'm just proud to be alive and hope that people realise that. I really sincerely thank everybody for the prayers."

Born near Bakersfield, California, Haggard rose to fame in the 1960s and became known for creating the Bakersfield sound, alongside fellow musician Buck Owens.

He scored hits with tracks like Okie From Muskogee, If We Make It Through December, Mama Tried, and the politically-charged The Fightin' Side of Me.

He was inducted into the Country Music Hall of Fame in 1994.

Tributes have already started to pour in from Haggard's famous fans.

Country singer Dierks Bentley took to Twitter to write, "literally just fell to the floor. can't believe we lost the hag. rip Merle Haggard," while Brad Paisley added, "There are no words to describe the loss & sorrow felt within all of music with the passing of Merle Haggard. Thank God for his life & songs."