Williams, 36, left the chart-topping boy band in 1995 and went on to forge a successful solo career. But his fortunes have waned while Take That, which reformed without Williams in 2005, has flourished.
Whether the two sides would finally get back together has long been the subject of fevered speculation in the British press, and in July Williams confirmed he would be joining his old bandmates  to record an album due out in November. "We're talking about a tour right now -- hopefully next summer we will tour," Take That member Gary Barlow said.
Williams added: "There's some stuff on the cards but there's only so much we can talk about now. "There's big plans in the works, but when, where and what we're not allowed to say. Plus we don't really know."
In a BBC Radio interview, Barlow added: "This is our 20th year for all of us this year. So to do a one-off album, and maybe a one-off tour would be a great thing this year. "I think once we've done that Rob will go back to being Rob and we'll go back to being a four. I think it'll resume to how it was."
Williams and Barlow have written a new single "Shame," which is about their estrangement and had its first play on Thursday. Several fans have gone online to note what they saw as a similarity between the song and the Beatles' "Blackbird."
Williams described his nerves ahead of a meeting with the band in Los Angeles, after which he and Barlow had a long discussion about the split. "I spent the last 15 years thinking what I was going to say," said Williams, who has just got married. "We had that big chat and the most amazing thing happened at the end of it, we both said sorry to each other and we both meant it. "That's all we needed. It just lifted so much off my shoulders that I didn't know was still there."
Shame is released on October 4.
(Reporting by Mike Collett-White; Editing by Steve Addison)
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