The government has paid private companies more than £2.5m this year to help pick up people attempting to cross the Channel on small boats.
The measure, first reported in The Guardian, comes after criticism of the Royal Navy's involvement with migrants.
The Ministry of Defence (MoD) is planning a review of its assistance to the Home Office in January 2023.
A Home Office spokesperson said: "We will always ensure Border Force have the resource they need."
At least 25,000 migrants have crossed the English Channel to Kent so far in 2022, according to the latest figures from the MoD.
A week ago, almost 1,300 people made the dangerous journey, setting a new daily record.
Contracts with two firms have been published on the government's website.
The largest, is a £1.98m contract with Aeolian Offshore Ltd, a company based in the Isle of Wight.
The contract is for three vessels to be stationed at Ramsgate, Kent, and to respond to callouts over a six month period, until 10 January.
It says the vessels will "depart from Ramsgate each day and proceed to reported sightings... to collect the migrants found," adding that they "may work alone, or in tandem" with Border Force.
Ian Baylis, managing director of Aeolian Offshore, said it bid for the contract "on the basis that it secures employment for our vessels and therefore crew, but also we felt this work was an important thing to be able to assist with, given the importance of the humanitarian element".
A Home Office spokesperson said: "We do not comment on operational matters.
"However, we will always ensure Border Force have the resource they need to protect our borders, including cracking down on the unacceptable small boat crossings and to save lives in the Channel."