Emily Thornberry has faced swift criticism for calling the Liberal Democrats “kind of Taliban” over their demand to cancel Brexit instead of holding a second referendum.
The shadow foreign secretary said the Lib Dems were ignoring democracy with their pledge to revoke Article 50 and she hoped Labour would campaign to remain in a second vote.
“The Lib Dems have gotten kind of Taliban, haven't they? They've said they're just going to revoke, there's not going to be another referendum,” she said.
“I don't think it's very democratic to seek to overturn a referendum without asking the people first.”
Liberal Democrat leader Jo Swinson said comparing a British political party to the Taliban was “ludicrous”.
“Emily is the shadow foreign secretary, and should use language that reflects the importance of that role,” she said.
Foreign affairs spokesman Chuka Umunna said comparing his party to a terrorist organisation was “no laughing matter”.
If elected, Jeremy Corbyn has vowed to negotiate a Brexit agreement and take his deal to a national vote along with the option to remain.
However he has signalled he may not put his hand on the scale either way, despite pressure from outspoken Labour MPs to back remain.
Ms Thornberry said she will be putting forward the case for remain at the Labour conference which starts in Brighton on Saturday.
“Not everyone agrees with me, so we need to thrash it out. The party has to decide collectively,” she said.