The Premier League's bottom club hired the former Chelsea manager to become director of football and expected him to start work with manager Paul Hart on Monday.
But the Home Office are refusing to let Israeli Grant, 54, resume his career in England until his work permit application has been considered. Sportsmail understands that the delay could last around two weeks and should just prove a formality.
Not for Granted: Portsmouth's relegation-threatened players (above) could use the help of former Chelsea boss Avram Grant (below) but face an anxious wait
Portsmouth chief executive Peter Storrie confirmed that Grant had not been able to rejoin the club he left three years ago. Storrie said: 'Avram has not got his work permit yet and there is nothing we can do to speed it up.
'He has applied in the normal way and all we can do is wait and see what happens. It is annoying but these things take time.'
The problem centres Israel's position outside the European Economic Area which makes it illegal for him to work in Britain without an appropriate permit.
Former Chelsea manager Grant returned home to Israel after the press conference announcement of his appointment at Fratton Park to visit his sick father.
The Home Office said all work permit applications were considered on merit and none were rushed through.
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