Cabinet Secretary Sir Jeremy Heywood has said "there has been no contact from officials" with former No 10 policy adviser Patrick Rock following his arrest over allegations linked to child abuse images.
Responding to Labour's Jon Ashworth who wrote to him demanding further details, Sir Jeremy said he tried "to respond to your specific questions but, as you recognise, in doing so my overriding concern must be to avoid doing anything to prejudice or undermine an on-going police investigation."
He added that the decision not to reveal the claims was made to avoid “jeopardising either [the police’s] investigation or the possibility of a prosecution”.
More top news
A 61-year-old woman was taken to hospital with head injuries after the incident in Islington, north London.
Counting will begin on Saturday morning, with the result expected later in the day.
There have been a number of incidents involving heavy goods vehicles getting stuck and causing disruption in recent months.