Mourners hoping to see the Queen Lying in State have been urged not to travel to join the queue after wait times reached 25 hours overnight.
It's currently standing at 14.5 hours, and joining the back could be halted if wait times go up further.
Many remained undeterred and prepared to wait “as long as it takes” to see the Queen lying in state.
Those waiting in the queue, which now has its own weather forecast, faced temperatures of 7C just before 7am on Saturday, at which time the official queue tracker advised the public not to make the journey.
The Department for Digital Culture Media and Sport (DCMS) issued the warning at around 1.15am on Saturday, as the queue was nearing capacity.
Thousands of people waited in cold temperatures overnight as the line stretched back five miles from Westminster Hall to Southwark Park.
By 10am on Saturday, the DCMS was reporting the wait times had come down, to an estimated 16 hours - but had not issued any further guidance on travel.
Entry to the queue was paused for 40 minutes at 11.35am on Friday, with officials closing the gates of the park.
At 8am on Saturday, the DCMS tweeted: "The queue is in Southwark Park and wait times are at least 24 hours. If the park reaches capacity, entry to the queue will be paused."
A separate queue for people who have accessibility needs, or who cannot stand for long periods of time, has been closed until midday as "capacity is limited", the department said.
An official queue tracker has been released for mourners hoping to pay their respects to the Queen, showing a waiting time and an endpoint.
Downing Street said the queue system was going to plan, despite the vast numbers, and the queue has been moving steadily.
Undeterred, a steady stream of people joined the queue on Friday evening, many wearing coats and jumpers.
Tatie Kirst, 38, of Canada Water in south-east London, a project manager who had just joined the queue in Southwark Park, said: “Well, it’s a journey right?
Watch ITV News' continuous live coverage of mourners queuing to pay their respects to the Queen Lying in State in Westminster Hall
“I think I’m prepared, I brought my good coat, I have a stool if I need to sit, I’m getting food and water, and we’re going to walk the way. “I think there is always a question, Is it worth it? Can I make it? And hopefully, yes. I wanted to be part of this, pay my respect to the Queen.”
Despite yesterday's temporary closure, Linda Partridge, 71, and Simon Hopkins, 59, travelled down from the West Midlands for the Lying in State.
Ms Partridge, who had left home at 3am, said: “Even though they said it was closed I felt that need to come down.
“If we’ve got here and then they turned away, then fine. I would have just felt I needed to come and then be told I couldn’t go”.
Mr Hopkins added: “There was a sense of perhaps ‘best not travel’ but just to make the journey and just to check it out, and you know, if it ended in disappointment, and then so be it.”
He likened the experience to a “pilgrimage”, which he said, “is a bit strange, because that kind of goes against my grain. He added: “I’ve been kind of drawn into it.”
Those inside Westminster Hall were briefly shocked on Friday night when a man was arrested after moving out of the queue to approach the Queen’s coffin. Metropolitan Police said the incident occurred around 10pm, as the live feed from inside the hall cut away for a brief period.
The King and his siblings hold a silent vigil around the Queen's coffin as the public quietly files past - Emma Murphy reports
A statement from Scotland Yard said: “Around 22:00hrs 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.” James Birchall, 33, a trainee physiotherapist who travelled from Liverpool to pay his respects, was also queuing. He said: “Now I just feel normal and unemotional but as I get closer and closer (to the Queen’s coffin) I think I’ll start to become more emotional and maybe five minutes before I go in I’ll probably, even though I don’t look like the type of person, I’ll probably start crying. “I absolutely loved the Queen, she was great, she had been there all my life, I have always had respect for her. She was great for our country, always did her duty right until she died.
“When she died I was overcome with emotion and I thought, I have got to come to London to see it.”
On the thousands of people queuing, he added: “I’m absolutely amazed because there is so many people, young and old — I did not think young people would come, necessarily, because they are not really in tune with monarchy, but there’s so many young people here to pay their respects which I think is awesome.” Also queuing was Vlasta Picker, 73, of Bedford, who said: “I came here in 1977 on the Silver Jubilee. Growing up in central Europe, monarchy was a thing of the past, history. “I was really quite mesmerised, it was massive in 1977 and I have admired her ever since because she was a wonderful person, unique.
The remarkable life of the Queen remembered in our latest episode of What You Need To Know
“To serve all her life until the end, it’s something, isn’t it? Unprecedented. And that’s why I want to be here.” Figures from the London Ambulance Service (LAS) show that 435 members of the public were treated along the route of the queue to see the Queen lying in state and surrounding areas over the past two days. Some 291 people along the route of the queue and nearby in London were given medical assistance on Wednesday, with 17 needing hospital treatment, the LAS said. A further 144 people were treated on Thursday, with 25 people being taken to hospital. The LAS said the majority of incidents attended were faints and collapses, resulting in head injuries.