There is a "very real danger" Manston migrant processing centre could return to "unacceptable conditions" of overcrowding, a borders and immigration inspector has warned.
David Neal, independent chief inspector of borders and immigration, revealed his findings following a re-inspection of Kent holding facilities, including Manston and Western Jet Foil, in January and February this year, after finding Manston at "breaking point" in October 2022.
The watchdog chief said the Home Office has "started to get its act together" such as on qualified and trained staff, but that work remains to be done around strategy, data and training.
Accommodation levels were a key warning flagged in the report.
The inspector said: "There remains a very real danger, then, that a shortfall in the capacity of the accommodation estate will see numbers in Manston build up, with a return of unacceptable conditions resembling those seen in October 2022.
"I have received no clear answer from senior officials as to where the 55,000 to 85,000 people expected to arrive in 2023-2024 will be accommodated. I do not think that anyone knows yet. This is a considerable risk."
The report cited expansion plans for residential holding rooms at Manston where people could be detained for up to 96 hours, but that it will take several months before they are ready to use.
Mr Neal added that Home Office data collection on the initial processing of people arriving in small boats remains "inexcusably awful" but that a new leadership team is in place to face the realities of a "really complex, challenging summer ahead".
Mr Neal said reliable data was vital to focus on identifying vulnerable migrants and that this priority must continue regardless of rising pressure and number of arrivals.
He said: "I have witnessed at first hand compassion, openness, a willingness to face up to reality, and a preparedness to speak truth to power.
"While the forecast for arrival numbers for this year points to challenges ahead, I am more confident that the Home Office has started to get its act together."
But the watchdog boss also addressed the "elephant in the room" as to why it has taken so long to do so, adding: "More than four years after small boats began arriving regularly on the south coast, there is only now any sense of the kind of planning and operational delivery I would expect to see."
Mr Neal is planning to revisit Manston migrant centre when it is busier for another inspection this year.
The Labour Party's shadow home secretary Yvette Cooper said the report showed the Government's "appalling mishandling of the asylum system" that is putting "border security and vulnerable individuals at risk."
A Home Office spokesperson said they welcomed the report which shows "significant improvements" to the processing of migrants arriving by small boats at Western Jet Foil and Manston.
The spokesperson added: "This report acknowledges the great work already done by our staff and recognises the positive changes made across a range of areas including infrastructure, welfare support, biometrics, health screening and communication with migrants.
"As part of our ongoing work to stop the boats, we have already taken action to address the report's recommendations and we will continue to ensure there is sufficient onward accommodation to prevent overcrowding at Manston."