Fergie, who joined the group in 2002, hasn't recorded new music with the Peas in more than five years, so the writing has been on the wall for a while.
"Since the beginning of Black Eyed Peas, we've always had amazing vocalists that appeared on the mic with us. People like Macy Gray, Esthero, Debi Nova, Fergie. On 'Elephunk,' there were several females that appeared on that album," will.i.am told Ahlan! on June 1 when asked if Fergie had left the band.
"Obviously Fergie was the featured female, but on songs like 'Let's Get It Started,' it's Noelle [Scaggs] and then Fergie; songs like 'Latin Girls,' it's Debi Nova, and 'Request Line,' it's Macy Gray," he added. "We'll always work with good females."
Although the Peas plan to work with more female singers, the Fergalicious one is irreplaceable.
"As for replacing, what people know the Black Eyed Peas to be, nobody is replacing Fergie," he said. "She's working on her solo project at the moment; we're on this brand-new experience, celebrating 20 years of Black Eyed Peas putting out music."
"We worked on a bunch of songs on her solo record; we're proud that she has her label," he added. "But Black Eyed Peas are pushing it forward in terms of content, technology and experiences on our new project, [graphic novel] 'Masters of the Sun.'"
The source added, "Fergie reuniting with the Peas is pretty unlikely."
There has been a rumor of late that former The Pussycat Dolls front-woman Nicole Scherzinger could take over Fergie's duties.
"Nicole is on the new BEP project as well," will.i.am said. "I don't want to go into details how she's involved yet."