Pink Floyd are to release an album of never-before-heard material in October, lyricist Polly Samson has revealed.
Titled The Endless River, it will be based on sessions for the band's last studio album, The Division Bell, which was released 20 years ago.
The music will feature multi-instrumentalist Rick Wright, a founder member of Pink Floyd, who died in 2008.
Writing on Twitter, Samson called the record "Rick Wright's swansong" and described it as "very beautiful".
The writer, who is married to Pink Floyd guitarist David Gilmour, previously contributed lyrics to The Division Bell and Gilmour's solo album On An Island.
Pink Floyd later confirmed the album's release in a statement.
"It is an album of mainly ambient and instrumental music based on the 1993/4 Division Bell sessions which feature David Gilmour, Nick Mason and Richard Wright," it said.
"The album is produced by David Gilmour with Phil Manzanera, Youth and recording engineer Andy Jackson. Work is still in progress, but more details to come at the end of the summer."
Backing singer Durga McBroom-Hudson, who has toured with Gilmour and Pink Floyd, gave further details of the recording on Facebook.
"Yes, there is a new Pink Floyd album coming out and I'm on it!" she wrote, posting a photo of the recording sessions.
Prompted for more information by fans, she revealed that The Endless River consisted of "all unreleased songs" that had originally been planned for a side project called "The Big Spliff".
"It was originally to be a completely instrumental recording, but I came in last December and sang on a few tracks," she said.
"David then expanded on my backing vocals and has done a lead on at least one of them."
"I don't know if there will be a tour or not yet," she added. "Stay tuned."
The group, who have sold 250 million albums, last performed at the Live 8 concert in London in 2005.
Singer and bassist Roger Waters, who quit in 1985, continues to tour with productions based around the band's concept albums The Wall and Dark Side of the Moon.
Although he sued his bandmates in the 1980s, as part of an attempt to stop them using the Pink Floyd name, they appear to have reconciled in recent years, with Gilmour and drummer Nick Mason joining him on stage at the 02 in 2011.
Last year, Waters told the BBC his legal case had been a mistake. ""I was wrong! Of course I was," he said.
The new Pink Floyd album will be released separately from a 20th anniversary, six-disc box set of The Division Bell, which came out last week.