The newly promoted Magpies were desperate to keep hold of Cotterill, after he led them to the League Two championship, losing just one game in charge.
Moving on: Steve Cotterill resigned as Notts County manager on Thursday morning
But the 45-year-old, who rejected the chance to take over at Coventry City earlier this month, has signaled his intentions to succeed Avram Grant at Portsmouth, after quitting at Meadow Lane on Thursday morning.
'Leaving Notts County has been one of the hardest decisions of my career,' he said. 'It has been a real pleasure working with such a fantastic group of people.
On his way: Avram Grant left the Portsmouth post earlier this month
'The fans have been magnificent to me and I would like to thankeveryone connected with the club for how they have received me sinceI've been here and wish them all the very best in the future.'
Ray Trew, his chairman at Meadow Lane, said: 'The job that Steve did for us here will live long in the memory of all Notts County fans and, as is a mark of all great managers, he leaves the club in a much better position than when he arrived.
'Steve is a very ambitious manager and he feels that the time is right to take stock of his current situation before deciding upon his next career move, which I completely understand.'
Pompey administrator Andrew Andronikou revealed earlier this weekthat Cotterill is one of several managers being considered for thePompey job following the resignation of Grant.
'He is one of eight or nine managers that have been recommended tous. He was recommended by a third party,' Andronikou told theNottingham Evening Post.
'His CV precedes him. He is the sort of motivator that our playersneed to take them forward.'The fact he is out of contract at the end ofthe month is not a factor. We are looking for the right individual, notat their availability.'
Brendan Rodgers, Paul Ince and goalkeeper David James have also expressed an interest in the Portsmouth job.
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