Officials raised concerns that failing to move people to hotels was unlawful, sources tell the BBC.
Image source, PA MediaSuella Braverman failed to sign off on measures which could have eased pressure at a migrant processing centre, sources have told the BBC.
The home secretary was warned the government was acting outside the law by failing to sign off on ways to immediately move people to hotels.
Sources claim there was significant concern within the Home Office about the situation at the Manston centre.
The Home Office said claims advice was “deliberately ignored” were baseless.
Some 4,000 people are being held at a processing centre at the disused airport in Manston – when it was set up it was designed to hold 1,600.
Hundreds of people were moved there on Sunday after a fire attack at a separate migrant facility in Dover.
Migrants are only supposed to be kept there for 24 hours, but when the chief inspector of immigration visited last week, he found some people had been there for over a month. That included one family who had been there for 32 days, sleeping on mats in a marquee.
Sources familiar with the situation said Ms Braverman was urged to act to tackle the issues at Manston during her first spell as home secretary.
One source told the BBC there was “crystal clear” advice that the government was not acting within the law.
Sources told the BBC Priti Patel had been “reluctant” to sign off on sending asylum seekers to hotels when she was home secretary but did so because she was aware that it was her statutory duty to do so.
Grant Shapps is also said to have taken action to ease congestion at Manston during his brief period as home secretary.
But sources alleged that Ms Braverman did not take measures to ease overcrowding pressures by sending asylum seekers to hotels – despite warnings over the legality of what was going on at Manston.
Senior figures in Whitehall said the move was extraordinary and called into question whether Ms Braverman could survive in her position.
A Home Office spokesperson said: “The home secretary has taken urgent decisions to alleviate issues at Manston and source alternative accommodation. Claims advice was deliberately ignored are completely baseless.
“It is right we look at all available options so decisions can be made based on the latest operational and legal advice.
“The number of people arriving in the UK via small boats has reached record levels, which has put our asylum system under incredible pressure and costs the British taxpayer millions of pounds a day.”