Ministers came under fire from some on their backbenches for not seeking to push back small boats trying to reach England from France.
The Ministry of Defence (MoD) is expected to take over command of the operation from Border Force by the end of the month in a move signed off by Prime Minister Boris Johnson.
It comes as Ghana’s ministry of foreign affairs has denied being involved in talks with the UK about hosting a migrant processing facility.
Meanwhile in Dover, Kent, a group of people including a child aboard a small boat were met by Border Force just a few hundred metres from the port.
Defence minister James Heappey said military involvement is part of a wider plan from the Government, which will be announced in the coming weeks.
The current details are believed to have been announced as part of a Government bid to offer “red meat” to Tory MPs in a bid to drive attention away from Downing Street party allegations.
But Conservative former minister Sir Edward Leigh warned: “In the absence of ministers having the political will to use pushback, what is the point in appointing a Royal Naval admiral to help Border Force to be a more efficient taxi service so that the migrants will know that now ‘we have got the Royal Navy going to pick us up and we will be taken safety to the UK, and we will be put in a hotel and we will never ever be sent home’?
“This is just an embarrassment.
“Will the minister now co-ordinate with his colleagues to do what we have been suggesting for months now and that we get rid of the pull factors, namely we reform any piece of legislation that is necessary, including the Human Rights Act, and people who do this illegal crossing are arrested, put in a prison, and then deported?”
Mr Heappey replied: “His exhortations and those of colleagues have been heard.”
Conservative MP Philip Hollobone (Kettering) added in the Commons: “This isn’t Operation Red Meat, it’s Operation Dog’s Dinner.
“If the mission statement was to reduce the level of illegal people trafficking across the Channel, I’d support it.
“But the mission statement as far as I understand it is to lower the number of people landing on their own terms on UK beaches.
“So what the minister has effectively announced with the deployment of Royal Navy vessels is asylum seekers only need to get halfway across the Channel before being intercepted by the Royal Navy.
“This is going to incentivise people traffickers, they’ll see the Royal Navy ship on the horizon and they’ll say ‘point your dinghy in that direction, you only need to get halfway’ and the Royal Navy will pick them up.
“The only way this will work if the Royal Navy intercepts asylum seekers and returns them back to France.
“Without the second bit, this simply won’t work.”
Mr Heappey replied: “The last bit would be impossible without French permission and French permission has not been given.
“But I don’t accept his characterisation of what is being spoken about today.
“The MoD’s mission is to make sure nobody arrives in the UK on their own terms.
“It means nobody arrives in the UK without having been intercepted at sea or as they land.
“What happens next he’ll just have to wait a short while and I’m sure all will become clear.”
Tobias Ellwood, Conservative chairman of the Defence Committee, warned: “There is a real danger of mission creep here, with further naval assets being sucked into this challenge.”
Conservative former minister Mark Francois welcomed bringing in the military, but said: “If they are not going to be involved in pushback and they are not going to deploy sonic weapons, what are they actually going to do?”
For Labour, shadow defence secretary John Healey said the military are “there to protect the nation, not to protect Tory ministers”, and claimed the announcement “is the official confirmation the Home Secretary is failing”.
Labour MP Luke Pollard (Plymouth Sutton and Devonport) said: “The sonic weapons, the long-range acoustic weapons, are already fitted to Border Force vessels, so as the Royal Navy has now assumed operational control of Border Force, can he make the statement that no Border Force sonic weapons will be used for migrant crossings?”
Mr Heappey replied: “If Border Force vessels are fitted with a capability that the Royal Navy commander feels inappropriate for use, then he won’t direct that it is used, but that is his judgment.”
Also on Tuesday, Ghana’s ministry of foreign affairs denied being involved in talks with the UK about potentially processing asylum seekers.
The Times reported that plans are being drawn up to send people to countries such as Ghana and Rwanda for processing and resettlement.
But the Ghanaian government said: “The ministry of foreign affairs and regional integration wishes to state categorically that Ghana has not engaged with the UK on any such plan and does not intend to consider any such operation in the future.”
Shadow home secretary Yvette Cooper said: “Once again we find out that the Government has been making things up for the sake of headlines. Clearly, this was a desperate attempt to distract people from the Prime Minister’s mess, but this kind of behaviour from ministers is an embarrassment to our country and disrespectful to Ghana.”
She said: “Be it operation Big Dog or Red Meat or whatever schoolboy name they have for it now, it’s just ridiculous. Time and again the Home Office has been told that offshore processing is incredibly costly, impractical and damaging and it’s clear none of the countries they have approached have agreed. Yet instead of doing the serious hard work to tackle criminal gangs and prevent dangerous small boat crossings they just make things up to get headlines.”
More than 770 people have made the dangerous journey across the Channel in small boats so far this year, following a record-breaking year in 2021 when at least 28,000 arrived in the UK.