Tony Blair has said the Independent Group (TIG) of breakaway MPs are “courageous” but he will stay in Labour as he is “deeply attached” to the party.
Blair, a long-standing critic Jeremy Corbyn’s leadership, denied he was involved with TIG MPs' plan to split the party but said he had "sympathy" with them.
Speaking to BBC One’s Andrew Marr Show on Sunday, he added: “I’m in touch with them and I have spoken to some of them.
“I’ve got a great deal of sympathy with what they’re doing and what they’re saying.”
Luciana Berger, Gavin Shuker and others cited Corbyn's delay in taking a more pro-EU stance and the party’s failure to deal with anti-Semitism as among the reasons for splitting away.
It comes amid speculation more Labour MPs could be tempted to leave Labour to sit with the new group, for which Streatham MP Chuka Umunna is spokesman and three pro-EU Tory MPs joined last week.
Blair said he hopes to "bring the Labour Party back" to the centre ground.
He added: “I’m staying in the Labour Party. I’ve been in the Labour Party for over 40 years, I led it for 13 years, I was longest-serving Labour prime minister, I’m deeply attached to the Labour Party.
“But do I sympathise with what they have done? Yes, I do. I think they’re courageous in having done it.”
Blair said he is “deeply concerned” about Labour’s direction and policy, adding: “If you want to get back to winning ways, this is not the position to be in.”
He said he believed Labour deputy leader Tom Watson has “shown really great leadership” in recent weeks.
It comes amid reports Watson has set up a social democratic group within the party that will come up with policy ideas.
The deputy has also clashed with the party’s general secretary Jennie Formby over how anti-Semitism complaints are handled.
Blair added: “As a result of what he’s doing, he’s encouraging people who do share a perspective of the Labour Party as a governing, modern, progressive party, he’s actually encouraging them in a sense to stay because he’s providing a space within which people can debate and argue.”
The former PM also welcomed Labour’s switch to backing a second referendum on Brexit.
Blair added: “I think it’s absolutely inevitable that if you put the choice before the country - hard Brexit Tory party, hard-left Labour Party - it doesn’t matter what I say, what I want to happen, what anyone else says, you leave that amount of fertile territory open, someone is going to cultivate it.”