A man has been detained by police after a witness said he "ran up to the Queen's coffin" in Westminster Hall.
Witness Tracey Holland told Sky News: "Some person decided they were going to push my [seven-year-old niece] out the way, run up to the coffin, lift up the standard and try to do I don't know what.
"She was grabbed out the way and the police had him within two seconds."
She added: "Terrible, absolutely terrible, so disrespectful and unbelievable - and this poor little seven-year-old child, this is her lasting memory of the Queen."
The Metropolitan Police said: "Around 10pm on Friday 16 September, officers from the Met's Parliamentary and Diplomatic Protection Command detained a man in Westminster Hall following a disturbance.
"He was arrested for an offence under the Public Order Act and is currently in custody."
A parliament spokesman said: "We're aware of an incident in Westminster Hall, in which a member of the public moved out of the queue and towards the catafalque (raised platform).
"They have now been removed from the hall and the queue restarted with minimal disruption."
It comes after a 19-year-old man allegedly exposed himself and pushed into mourners from behind as they waited in the line at Victoria Tower Gardens on Wednesday.
Adio Adeshine was remanded in custody on Friday after appearing at Westminster Magistrates' Court charged with two counts of sexual assault and two counts of breaching a sexual harm prevention order.