The former Chelsea manager will succeed Paul Hart, who was sacked earlier this week.

Grant was the favourite for the position having returned to Pompey as director of football in October.

The Israeli will take charge of the first team for their Barclays Premier League home match on Saturday, but will remain in his capacity as director of football for the time being.

The south coast club will then go through the process of making the technical change that will allow Avram to become manager. This involves acquiring a new sponsorship number from the Football Association to change his permit status.

Portsmouth chief executive officer Peter Storrie told the club's official website: "Avram is a very experienced and respected manager who has managed at the highest level. The board believes he is the man to help steer the club out of the relegation zone.

"He knows the club, the players and the set-up at Fratton Park, so it was the logical move to make him the next manager, once the board had decided to relieve Paul Hart of the role.

"He will take charge of training on Friday alongside first-team coaches Paul Groves and Ian Woan."

Grant spent the 2006/7 season as Pompey's technical director before joining Chelsea as director of football. He became manager at Stamford Bridge and steered Chelsea to the Champions League final.

The 54-year-old rejoined Portsmouth as director of football in October subject to a work permit.

www.portsmouthfc.co.uk