LONDON - The British government came under increasing pressure on Monday to tackle deteriorating conditions at a migrant processing centre in southeast England a lawmaker said was "overwhelmed" by the numbers of people arriving across the English Channel.

Nearly 1,000 migrants arrived in Britain in small boats on Saturday alone, according to the Ministry of Defence.

Conditions at the site at Manston in Kent were last week described by Independent Chief Inspector of Borders and Immigration David Neal as "pretty wretched".

Intended to house around 1,500 migrants for less than 24 hours at a time, numbers have swelled to more than double that, with one Afghan family telling Neal they had been there for 32 days.

Neal told a parliamentary committee that out of 11,000 people who had gone through the centre in the past two months, there had been four cases of diphtheria.

On Sunday, a similar centre in the nearby port of Dover was attacked by a man who drove up and threw petrol bombs attached to fireworks before killing himself.

Local lawmaker Roger Gale, a member of the governing Conservatives, visited Manston on Sunday and said it had deteriorated significantly in recent days and weeks.

"It is overwhelmed," he told BBC Radio. "There are simply far too many people there and this situation should never have been allowed to develop and I'm not sure that it hasn't almost been developed deliberately."

Gale said a decision had been made in the Home Office not to book hotel accommodation to house migrants and he had requested that a government minister explain the situation to parliament.

Asked if some believed worse conditions would put people off travelling to Britain, Gale said: "I would say that is wholly unacceptable ... we need a grown up solution to what is a very real problem."

A spokesperson for Britain's Home Office, the government department responsible for immigration, crime and policing, said the number of arrivals via small boats was putting the asylum system under "incredible pressure".

"Manston remains resourced and equipped to process migrants securely and we will provide alternative accommodation as soon as possible," the spokesperson said.

New British Prime Minister Rishi Sunak's office last week said he had discussed the issue of clandestine migration across the Channel with French President Emmanuel Macron.

Charlie Taylor, the chief inspector of prisons, said the Home Office needed to "get a grip", and he would be returning to the site soon after inspecting it over the summer.

"They need to speed up the processing of migrants, they need to make suitable provisions so people can be moved off site as quickly as possible and housed in humane and decent conditions," he told BBC Radio.

(Reporting by Kylie MacLellan; Editing by Alison Williams)