At the last count, 65 under-18s were being held, despite Coalition pledges to end the practice. However, the SNP said the official figures exclude a significant number of youngsters who arrive unaccompanied and are wrongly detained as adults.
Ending the practice was a key Liberal Democrat pledge during the 2010 General Election campaign. Later that year, Nick Clegg announced: "We are ending the shameful practice."
SNP MP Pete Wishart said the figures were an absolute scandal.
"These are families who are often fleeing violence in countries like Iran, Afghanistan or Syria. What kind of country locks up children?" he said.
"There is no excuse for putting children under lock and key, and there is plenty of evidence of the severe mental and physical damage which it can cause."
The figures show that, in the third quarter of 2013, 65 children entered detention, up from 52 in the third quarter of 2012.
In the third quarter of 2012, 52 entered detention. The figure has risen steadily since a low point of 19 at the start of 2011. The highest number was 66, in the second quarter of 2012.
The Home Office insists the numbers are substantially lower since the Coalition Government came to power in 2010.
The Scottish Government has said it would create a Scottish Asylum Agency in an independent Scotland.