The Government has been accused of not moving quickly enough after it said it would take up to 20,000 refugees, with as many as 5,000 in the first year.
Ms Patel told Sky News: “We have to ensure we have the support structures throughout the United Kingdom We will be working with local councils throughout the country, the devolved governments as well.
“We are working quickly on this. We cannot accommodate 20,000 people all in one go.
“Currently we are bringing back almost 1,000 people a day. This is an enormous effort. We can’t do this on our own. We have to work together.”
But she hinted the scheme could be expanded to admit double the initial figure for the first year.
“There could be up to 10,000. We are expanding categories of people,” she said.
Speaking to BBC News, she added: “We could end up bringing many more but first of all we have to have the underpinning and the infrastructure and the support to do that.”
The Prime Minister’s official spokesman said the figures were not a “hard cap”.
At a Westminster briefing, he said: “The figure is based on our previous experience and what our expectations are of how many people will be able to both be seeking to leave and be able to leave over that time period.
“I think it’s important to emphasise that it’s very rare that people want to leave where they live and start life in another country, that’s why it’s right to have humanitarian support in the region, and it’s also right to use G7 and international diplomacy to hold the Taliban to account for their actions and for those promises and pledges they’ve set out.”
Ms Patel also told BBC Radio 4’s Today programme it will “take time” to get the scheme up and running, which will “not be straightforward”.
The United Nations High Commissioner for Refugees (UNHCR) agency, welcomed the announcement and said: “We look forward to hearing further details, and will work with the Government to resettle people in need.”
But UNHCR spokesperson Laura Padoan added: “However, the UK also needs to preserve the right to asylum for Afghans and others arriving spontaneously in the UK, a right under threat from the Nationality and Borders Bill returning to Parliament next month.
States have a legal and moral responsibility to allow those fleeing Afghanistan to seek safety, and to not forcibly return refugees. https://t.co/JxurSyNmqO
— UNHCR, the UN Refugee Agency (@Refugees) August 18, 2021
“Afghans or other refugees should not be criminalised because of the way they arrive. It would be contradictory to recognise that Afghans are facing danger and are in need of protection but then punish them should they make their way to the UK.
“The UK, like all other countries, has a legal and moral responsibility to allow people to seek safety on its shores.”
The Government’s planned overhaul of the asylum system, dubbed the anti-refugee Bill by critics, intends to make it a criminal offence to knowingly arrive in the UK without permission, with tougher sentences for those found doing so and for people smugglers.
It means, for the first time, how someone enters the UK – legally or “illegally” – will affect the progress of their asylum claim and their status in the UK, if their bid is successful.
Aalia Khan, from charity Freedom from Torture, described the numbers pledged in the scheme as a “fraction” of the help that could be given and said that assistance was needed “right now”.
She added: “The desperate scenes in Kabul are a stark reminder of why Britain must not break international commitments and overturn the principle of asylum. Our message to this government is clear: Scrap the anti-refugee bill, save refugee lives.”