The Tory minister was quizzed after terror suspect Daniel Khalife was finally recaptured after three days on the run.
The former soldier managed to escape from Wandsworth Prison in London by strapping himself to the bottom of a delivery van.
Ministers have faced intense criticism over the state of security at the jail.
On Sky News this morning, Phillips told Chalk: “We don’t have enough prison staff - you’re trying to recruit more.
“Of the ones that we do have, a lot of them are off sick, with the number of sick days claimed since 2018 annually is up 60%.
“And here is the most concerning thing perhaps. Of those who are on duty, a high proportion are inexperienced. Overall one in six are in their first year in the job.
“Add it up - isn’t this a system designed for a disaster?”
Chalk - who revealed that 40 inmates had been moved from Wandsworth in the wake of Khalife’s escape - insisted the government was determined to make working in the prison service an attractive profession.
He said: “The condition of our prisons is of course very important. This is the government that has done more to put its money where its mouth is to invest very heavily in our prison service.”
Chalk added: “We accept that they are phenomenal people who do an extremely difficult job. We value them hugely and I really want to encourage people into the service.”