Sources said that RoDMA is expected to confirm its opposition to the asylum barge in the coming weeks after taking soundings from its owners. It will be agreed at an upcoming board meeting before a formal rejection is issued to the Home Office.

It is understood that the Home Office could still press ahead without the blessing of the London mayor and the Royal Docks authority – but this would likely require a change of law.

If Ms Braverman were to insist on selecting the Royal Docks, the asylum seekers would be moored on the barge within a stone’s throw of the airport’s runway. Flights begin at 6.30am and run until 10.30pm on weekdays, 6.30am to 1pm on Saturday, and 12.30pm to 10.30pm on Sundays.

The airport is consulting on extending operating hours. It is currently restricted to handling up to 6.5 million passengers and 111,000 flights annually.

Rishi Sunak confirmed on Monday that the UK had acquired two more barges on which to house asylum seekers as part of plans to crack down on illegal immigration. They are reportedly to be moored in Liverpool and near Middlesbrough.

In addition to the Royal Docks, the Home Office has also identified Newcastle, Harwich and Felixstowe as locations to house migrants. 

The Prime Minister has claimed that an immigration crackdown is “starting to work” as figures revealed a 20pc fall in the number of asylum seekers making the crossing compared with last year.

But the use of barges has been criticised by members of Mr Sunak’s own party. Richard Drax, the Conservative MP for South Dorset, attacked the “quasi-prison” conditions and Lee Anderson, Conservative party deputy chairman said using barges as well as forcing asylum seekers to share rooms was “not the answer”.