Diane Abbott says she has been barred from standing as a Labour candidate at the general election.
The veteran Labour MP had the party whip restored on Tuesday, but will not be able to stand for it on 4 July, she told the BBC.
Ms Abbott was suspended last April over a letter she wrote in The Observer suggesting Jewish people are not subjected to the same racism as some other minorities.
The former shadow home secretary under Jeremy Corbyn immediately apologised over her comments and said the letter had been an “initial draft”.
But she was suspended by chief whip Alan Campbell and placed under investigation.
It emerged on Tuesday that the investigation into Ms Abbott had concluded in December, despite Labour leader Sir Keir Starmer insisting this month it was still “ongoing”.
She then had the party whip restored, meaning she can retire as a Labour MP, but will not be able to stand for the party in the general election. She told the BBC: “Although the whip has been restored I am banned from standing.”
In the letter which saw her suspended, Ms Abbott suggested Jewish people are not subjected to the same racism as some other minorities.
It stated that Jewish, Irish and traveller communities have experienced “prejudice”, but added: “This is similar to racism and the two words are often used as if they are interchangeable.”
Ms Abbott had added: “It is true that many types of white people with points of difference, such as redheads, can experience this prejudice. But they are not all their lives subject to racism.”
Labour’s decision to block Ms Abbott from standing marks the end of the Hackney North and Stoke Newington MP’s 37-year career, unless she follows in the footsteps of Mr Corbyn and runs against the party as an independent.
A Newsnight report on Tuesday said the investigation into Ms Abbott was completed in December, with the veteran MP given a formal warning over her conduct and required to complete an antisemitism awareness course.
Friends of Diane Abbott have demanded to know if Sir Keir Starmer and the Labour leadership have been dishonest in the way they have treated Diane Abbott.
Ms Abbott’s friend Jacqueline McKenzie, an immigration lawyer at Leigh Day, told Radio 4’s Today Programme: “I think Diane’s really shocked. She has been for a very long time because this investigation has gone on for 13 months.
“I think those around her were quite surprised yesterday to learn that the investigation had concluded in September. It is not clear to me that she knew the investigation had concluded but I certainly saw some surprise in some of her exchanges.
“But I think what was really astonishing about all of that was the fact that just this week we saw Keir Starmer, the leader of the Labour Party, as well as senior officials saying that an investigation was still underway.
“I think it is really incumbent upon them to explain have they been honest about this process. I think that’s what really shocking.”
Sir Keir has come under mounting pressure to restore the whip to Ms Abbott, including from Labour deputy leader Angela Rayner and mother of the House Harriet Harman who have said they want her back in the party.
Shadow health secretary Wes Streeting was asked about Ms Abbott being blocked from standing and said he was glad she had the whip restored but “what she said that led to her suspension was wrong”.
Mr Streeting said: “When Keir Starmer said he would restore discipline and standards in the Labour Party, he really meant it.”