Transit visa by a Nigerian national

Kindly help me out. I am a Nigerian with a Nigerian passport and I need to transit at Hong Kong Airport for 7 hours before I depart for another country, I hold a valid work permit for the other country. I was told that I require a transit visa for Hong kong by the Airline agent but from what I see, I dont.

Pls can you advise me if I need a transit visa for staying at the airport in Honk Kong as a Nigerian I really need your advise urgently because I have just 3 weeks left before my visa expires.