Diane Abbott says she's "beginning to worry" about Labour's Brexit strategy.
The Shadow Home Secretary - one of Jeremy Corbyn's closest allies - took to Twitter to say she was concerned about whether the party had got its strategy right.
Her intervention will add to the pressure on the Labour leader to fully embrace a second EU referendum - something he has so far resisted.
It follows a reportedly fractious shadow cabinet meeting on Tuesday when Mr Corbyn again delayed a decision on whether the party needed to change course.
Following Labour's dismal showing in last month's European elections, deputy leader Tom Watson and shadow foreign secretary Emily Thornberry have both publicly called for the party to come out in favour of another public vote.
Shadow chancellor John McDonnell, another of Mr Corbyn's close allies, is also reported to have voiced frustration at the continuing stalemate on the issue.
Responding on Twitter to a tweet expressing concern about Labour's stance, Ms Abbott said: "Like you I have supported Labour's Brexit strategy so far. But like you I am beginning to worry..."
Mr Corbyn yesterday allies after kicking his decision on a second referendum down the road.
He had been expected to announce that he was backing a fresh public vote in all circumstances - and that Labour would support Remain.
But after a crunch meeting with the unions - including powerful Unite chief Len McCluskey - Mr Corbyn opted to delay for several weeks.
