Take That have claimed they did not notice Robbie Williams' struggles with addiction when he was in the band.
Williams went on to have a hugely-successful solo career after leaving Take That in 1995, but was already in the grip of drug and alcohol dependency.
The singer went public with his problems and eventually recovered with a spell in rehab, but the band feel they should have paid more attention to his predicament.
Speaking to the Sun, Gary Barlow said: "That's my one regret. I missed the signs. I think we all did.
"He's One Of Us still, so I feel sorry for him and my natural instinct is to help him. His life could be better."
Mark Owen added that they used to joke that Robbie wanted to be in OASIS, without realising that he was actually adopting such a lifestyle.
It was recently reported that Robbie is considering joining his bandmates for a planned movie charting the success of the band.