Metallica's Kirk Hammett says prog rock music paved the way for heavy metal.

The axe-slayer says heavy metal would sound "different today" if it wasn't for the progressive genre of rock music's influence.

Appearing on the 'Kyle Meredith with... ' podcast, he said: "I'm super influenced by classical music and prog these days.

"I just discovered prog by the way, I just never got around to listening to it, and then a few years ago I was just like, Hey, I need to start listening to this stuff, because this stuff is really cool and important and instrumental in what, you know, heavy metal is today. I think you can definitely draw a line there, especially with the early prog: I mean, if it wasn't for that early prog, you know, heavy metal would sound different today... the prog influence was huge."

Reeling off the list of prog acts he has more recently gotten into, he added: "I've always been a Rush fan, but I never really listened to, you know, Yes, Jethro Tull, Genesis, King Crimson... all those kind of affiliated bands. At one point I was just like so into Yes, it was all I listened to for like a couple weeks, it was like driving everyone crazy around me. But you know it's just great stuff, really instrumental and important stuff."

For the band's latest tour, Kirk has been improvising his guitar solos.

He previously shared his intention to play "something completely different" at their concerts - and if the fans don't like it, Kirk insists that's "tough".

He told Total Guitar magazine: "I have every intention on playing every solo from this album differently whën we play live.

"If you watch old videos of Ritchie Blackmore, Jeff Beck, or even Michael Schenker, they're not playing the solos on the album - they're playing whatever the f*** they wanna play. I love that because it's a moment of real honesty.

"With this album ['72 Seasons'] I went in intentionally to improvise 20, 30 solos, give them all to Lars [Ulrich, drummer] and Greg [Fidelman, producer], and go 'You guys edit them!' I know I'm gonna play something completely different live, so I can offer something different every time you see Metallica. When you buy a ticket to a Metallica show, you're not gonna hear carbon copy versions of the album."

He continued: "At a time when it's just so accessible to see videos of your favourite band, there needs to be some sort of impetus for people to go out and see live shows that are actually somewhat spontaneous."

Kirk concluded: "That's my thing these days - and if people don't like it, that's just tough!"