Kirk Hammett has announced his debut solo EP, 'Portals'.

The Metallica guitarist has unveiled his upcoming cinematic collection, which saw him co-write with renowned conductor Edwin Outwater.

He said in a statement: “This music was created with what I describe as an Audio-Cinematic approach. They’re soundtracks to the movies in your mind.”

A press release states that the EP is "a collection of gateways to myriad musical and psychic destinations. Recorded in multiple locales ranging from Los Angeles to Paris to Oahu, 'Portals' is both the result of musical and metaphysical journeys. An invitation to inner worlds accessible only by music and the psyche it fuels."

Kirk, 59, also produced the four-tracker - comprising the instrumentals 'Maiden And The Monster', 'The Jinn', 'High Plains Drifter' and 'The Incantation' - while Edwin contributed keyboards and leads the orchestral players.

Kirk previously worked with the LA Philharmonic on the heavy metal titans' 'S&M2' concerts and releases.

Emmy-winning arranger Blake Neely and Metallica's long-time producer Bob Rock were also involved.

'Portals' is set for release on April 23 digitally, on CD, and as a Record Store Day Exclusive Ocean Blue Vinyl EP.

As for new Metallica music, Lars Ulrich insisted in October that while it's in the works, they had "nothing cohesive" yet.

The heavy metal behemoths - also including James Hetfield and Robert Trujillo - re-released their landmark self-titled album ('The Black Album') to mark its 30th anniversary, and dropped the star-studded 'The Metallica Blacklist' covers compilation in September.

And though fans can expect some new music at some point, the material they had worked on for a new album wasn't ready to become one package at the time.

The 58-year-old drummer said: "There's nothing cohesive. There's not a story. There's not really anything to back it up yet."

The sticksman had previously insisted the heavy metal group - who formed in 1981 - have no plans to stop making music because they love the "creative process" and always strive to make each new album better than the last.

Asked if they'd thought about their plans for their follow-up to 2016's 'Hardwired... To Self Destruct' yet, he said: "It’s going to be the best album we’ve ever done! Insert the rest of the clichés – it’s the heaviest thing, the coolest…

"But all kidding aside, if it wasn’t because we thought that the best record was still ahead of us, then why keep doing it? In Metallica we love the creative process, and it’s hard for me to imagine that we’ll ever stop making records."