"A total of 32 people are now here, including one of (Gaddafi's) sons, Saadi, as well as three generals," Brigi Rafini said during a meeting with foreign diplomats in Niamey.
The arrivals had crossed the border in four separate groups over the last 10 days and had been taken in by Niger for "humanitarian reasons", the prime minister added.
The most recent arrivals included Saadi and eight other close associates of Gaddafi senior, added Rafini in comments carried out by public radio.
Other sources told AFP earlier Monday that Saadi "still hasn't reached (the northern regional capital) Agadez and is somewhere in the desert".
Muammar Gaddafi, his most prominent son Seif al-Islam and his intelligence chief Abdullah al-Senussi are all wanted by the International Criminal Court for alleged crimes against humanity.
But Rafini said none of those known to have crossed over the border were being sought by the Hague-based war crimes court.
"As far as we are aware, none of the 32 in Niger are being sought on an arrest warrant or being pursued by international justice," he said.