Guy Whittingham has ruled out promoting Dan Thompson into the first-team – for now.
The Blues currently have two spots available in their squad and are searching for players to bolster their numbers.
A striker remains a top priority, with Izale McLeod and Ashley Harris the only options for the caretaker manager for that role.
The name of Thompson has repeatedly been put forward by fans in recent weeks as a potential candidate.
The towering 18-year-old scored four goals in a friendly against Gosport last month and is highly-rated.
Both Whittingham and Andy Awford know all about him, having worked with the youngster through their roles with the development group and Academy.
But while Thompson is well thought of, the Blues boss does not yet believe he is ready for a first-team berth.
Instead, he will focus on bringing in more experienced striking talent.
‘We have enquired about putting Dan up but the problem is if we put any of the development group players on the bench they would be classed in the 20-man squad,’ said Whittingham.
‘For me and Andy it is a real disappointment because we want to involve them.
‘But for the moment, do you involve them in the 20 or try to get someone who is proven at this level? That is the balancing act.
‘It’s a shame for those lads, but that’s where we are and what we are going to do with them.
‘They are not ready for League One football, that’s the thing.
‘In an ideal situation, they would be part of your 18-man squad and you might give them five minutes to give them experience.
‘You would get them to travel with you to learn what being with the first team is all about.
‘But they are not ready. Jed Wallace is not ready, Dan Thompson is not ready.
‘People might say “how do you know they are not ready until they are in it?”
‘Well, it’s because we see them play against Gosport and there are little things in those games they get away with that they wouldn’t get away with at this level.
‘We understand that, we know what we are looking at. It’s all right taking a gamble and putting them in but you need to do that when the time is right.’
Several playing colleagues of Thompson are currently out on loan to non-league clubs.
Wallace is now in his second month at Whitehawk, having scored six goals in his opening seven matches.
Dan Butler is impressing at left-back under Lee Bradbury at the Hawks.
Meanwhile, Elliot Wheeler has joined Bashley for a month, although suffered a leg injury on his debut.
In the meantime, youngsters like Thompson must make do with development group friendlies for match action.
Whittingham added: ‘It might be two or three weeks down the line that we can include them and hopefully we will be able to.
‘It’s not said and done about not putting them in at present. It’s not something we are dead sure about.
‘It’s just where we are thinking at the moment.’
Pompey’s squad will have a 20-man restriction until the club comes out of administration.