The Italian is quitting to work for a group which focuses on acquiring football clubs across Europe.
Cullen has praised the ‘great’ work from Gagliardi, who initially took the Blues job on an interim basis in March 2021 following Kenny Jackett’s dismissal.
Fratton Park’s chief executive believes the soon-to-be-vacant position is pivotal to Pompey’s ambition so will be retained.
And the hunt is on for Gagliardi’s successor.
Cullen told The News: ‘Roberto is leaving the club to work for a group which owns two or three clubs in Europe – and is looking to acquire some more across the continent.
‘He will probably focus on identifying the type of club the group should be looking to acquire.
‘Roberto has quite big respect in European football through his network and his contacts. The European market was an area initially he came into Pompey to look at, but Brexit changed things slightly in terms of narrowing the pond for younger European players coming in.
‘Roberto has done a great job for us, he’s responsible for bringing Ronan Curtis to Pompey and is really, really hard working.
‘Now we are looking at how to take that head of football operations role onto the next stage, but 100 per cent the position will remain.
‘It’s really, really, important, taking a bit of pressure off Danny and me in terms of having someone there who is totally focused on the day-to-day aspects and also from a long-term perspective, which has to be beneficial for Portsmouth Football Club.
‘The role is part of where we want to be, whether it be head of football operations, sporting director, recruitment director, it’s about what can work best.
‘It won’t be somebody who reports into Danny and it won’t be somebody who Danny reports into, the two will be quite separate. Instead that person will report directly to me.
‘I am totally open-minded about where his replacement comes from. We have already started the process and will be looking across the game, not necessarily limited to England either.’
Gagliardi formerly worked in recruitment for Leyton Orient and Bolton before arriving at Pompey in March 2018.
He was appointed head of European scouting and is credited with spotting Ronan Curtis at Derry City, helping bring him to Fratton Park in May 2018.
Talking about the ideal candidate to replace Gagliardi, Cullen added: ‘We want somebody who can give us a strong backbone in terms of recruitment networks, has relationships with people throughout the industry, and someone aligned to where we want to go.
‘We are looking at the scope of the role beyond recruitment as well.
‘That person must make sure we have real alignment between the Academy and the first-team, which is a project Roberto has already started with Greg (Miller) and Danny - and been successful in terms of progress.’
A message from the Editor, Mark Waldron
You can support our local team of expert Pompey writers by subscribing here for all the latest news from Fratton Park for 9p a day, thanks to our 30%-off transfer window deal.