Forest placed first team coach Paul Williams in temporary charge after Dougie Freedman was relieved of his duties in March.
Former Standard Liege boss Ivan Vukomanovic held talks with the Reds last month, according to Belgian reports, after the Nottingham Post claimed a foreign appointment was favoured by owner Fawaz Al-Hasawi.
However, the Kuwaiti said last week that Forest were in talks with two experienced British managers, both of whom have Nottingham links and had previously taken clubs into the Premier League.
But if the Sun's report is accurate, it could be some time before the identity of the new man is revealed.
The tabloid claims the hold up is due to the fact that prospective buyer Evangelos Marinakis is keen to appoint his own man.
Marinakis is the current owner of Olympiakos but the Sun reported in March that the Greek shipping magnate, who has a house in London, is keen to add a major club to his portfolio.