Children under the age of five are being fingerprinted at asylum centres amid fears that some families are trying to claim extra benefits.
Young children are being fingerprinted with "wet ink"
In the past only children who are five-years-old and above have been fingerprinted because of problems in scanning very small fingers.
Now the Home Office says it is holding trials for younger children at asylum centres in Croydon and Liverpool.
It is feared some children are being registered by several families.
The trials, which began in February, will test whether using the traditional "wet ink" fingerprinting can work for children under-five. Most prints are scanned digitally.
If successful, the scheme could be rolled out nationwide.
The prints will allow officials to check children suspected of being used by different families against prints taken in the past.
A Home Office spokesman confirmed a report about the trials in Computer Weekly magazine.
He said: "We have set a lower limit of five for the fingerprinting of asylum seekers because of the practical difficulties of taking and matching fingerprints from under-fives. That is to do with how small the prints are.
"We are conducting trials in two asylum centres, in Croydon and Liverpool, to assess whether fingerprinting can be used effectively for under-fives.
"We are using the traditional wet ink approach whereas normally we would do it digitally.
"The reason we are doing this is because we have suspicions that children are being registered by several families in order to claim more support."
A spokeswoman for the Joint Council for the Welfare of Immigrants said she would like to know the evidence of benefits being used to justify "that kind of intrusive action".
She was also concerned that fingerprints taken from children and kept on immigration databases might count against them if they tried to re-enter the UK later in life.