"Several hundred" more children will arrive in Britain from Calais's "Jungle" camp in the next three weeks, Home Secretary Amber Rudd has said.
She told MPs they would be in addition to the 200 children who had already arrived - which included 60 girls, many at risk of sexual exploitation.
Mrs Rudd blamed delays in processing vulnerable children on French officials not granting access to the camp sooner.
Labour's Diane Abbott accused the Home Office of "hiding behind the French".
It comes as nearly 2,000 migrants have been bussed away from the Jungle and about a third of the camp cleared, as French authorities have begun to move into the area.
Addressing MPs, Mrs Rudd said the children chosen to come to the UK would be selected on the basis of three factors - how likely they were to be granted refugee status, whether they were aged 12 years or under, and whether they were at high risk of sexual exploitation.
Britain will not consider any children who arrive in the Jungle after the process of clearance began, she added, to discourage more from travelling to Calais.
She told the Commons, 800 children had already been interviewed by UK officials in the camp - saying some interviews with children had to be "paused" for staff safety reasons.
Between "200 to 300 more" would be interviewed in the coming weeks, she said, but added that not all of them would come to the UK.
Almost 200 children had been brought to the UK so far, including those with family connections in the UK - under the EU-wide Dublin arrangement - as well as vulnerable children - under the Dubs amendment.
She indicated that unaccompanied refugee children will not be allowed to sponsor their parents to come and join them in the UK.
Clearing the Jungle would be a " huge challenge", Mrs Rudd said, saying the UK government would be contributing £36m towards efforts to permanently close the jungle and maintain security in Calais in the long term.
She said it was in the UK's "national interests" to close the Jungle, saying it would secure the UK's agreement to carry out immigrations checks in Calais, rather than in the UK - under the Le Tourquet agreement.
She told MPs: "The rise in the number of people has led some in France to question the Le Touquet agreement.
"This agreement has helped us better protect our borders, and ensured strong trade links between Britain and France. By clearing the camp, we can help secure the future of the juxtaposed controls, as well as playing our part to help those most in need in Calais."
However, Labour's shadow home secretary Diane Abbott said the UK had refused for "far too long" to assess children in the camp, saying people in the camps had been used as "pawns".
It comes as the charity Help Refugees said it knew of 49 children under the age of 13 who were eligible to come to the UK, but remained in the camp.
The charity said amid the "confusion and chaos" inside the camp, some accompanied minors were still there - including unaccompanied girls eligible and waiting to be registered.
Up to 1,000 children were expected to be housed in shipping containers at the camp, but some had in fact been evicted from the containers, Help Refugees added.
Others had been told to queue to register with officials, while some had been told registration had closed for the day, it said.
"This chaotic set-up is extremely distressing and confusing for the lone minors, the youngest of which is eight years old", the charity said.
"The younger children are struggling to understand where they are supposed to go, and how they are supposed to get there."
Lord Dubs - who first proposed an amendment to immigration legislation to allow vulnerable young children entry to the UK - told the BBC he hoped the Home Office will move "very quickly" to remove those still in the Jungle.
"It is a terrible thought that these are young children who have got no future as far as they can tell unless they come here," the Labour peer said.
He said Britain should not have to do everything, but "should play our part" in helping children in Calais, as well as those in Greece.
Lord Dubs hailed the fact that dozens of youngsters had arrived in Britain last week under a fast-track scheme designed to bring unaccompanied minors from the French shanty town.
Devon County Council has confirmed 23 child migrants have arrived at a "respite centre" in the county
Meanwhile, the closure of the "Jungle" camp has been welcomed by the Road Haulage Association.
However, Kate Gibbs, from the organisation, told BBC Radio 5 live that a longer term solution to the problem was required.
She said "thousands and thousands" of migrants were still making their way to Calais, saying it was a "beacon" because it "is on our doorstep".
Ms Gibbs said drivers passing through Calais had been attacked, including with scaffolding poles. One female driver had been threatened with rape, she added.
In its travel advice, the UK Foreign Office says it is aware of recent incidents of "obstacles" being placed on main roads and items being thrown at vehicles in Calais.
It advises drivers to "keep moving where it's safe to do so", to keep vehicle doors locked in slow moving traffic in and around Calais, and to secure all unattended vehicles.