Djeziri, 19, has signed from Boldklubben Frem after spending the first part of the season on loan at Leicester City. Last season he was part of Rangers' under-19 side that won both the Scottish Youth League and Cup.
Pompey have also confirmed that South Korean striker Cho Jae-Jin is on a weeks trial at the club with a view to a transfer after he rejected a new deal with Shimizu S-Pulse.
The 26-year-old has scored 34 goals in the J-League for S-Pulse and has 8 goals for his national side having earnt 29 caps.
I can't say I know much about Jae-Jin only that he is loved by South Koreans, can also play on the wings and he's absolutely rubbish on Pro Evolution Soccer 2008.