Flying Eagles Coach, John Obuh, has said all 12 new invitees have to report to the team’s training camp in Abuja latest Thursday.
“We are building a new team almost from scratch and as such we have to be very prompt in anything we are doing,” said Obuh.
He added: “I therefore expect the new players I have called up to report to camp unfailingly on Thursday or else forget being part of my team.”
The Nigeria U20 team are due to feature in an invitational tournament in Cape Town, South Africa, from May 24.
The Flying Eagles, who are the African U-20 champions, won the inaugural competition last year.
The 2011 FIFA U-20 World Cup quarter-finalists are also scheduled to tackle the winners of the qualifying match for next year’s African Youth Championship between Tanzania and Sudan at the end of July.
On Wednesday, as part of their preparation, the team defeated Mountain of Fire FC 5-0.
The Flying Eagles goals were by Samson Yohanna (Jigawa Golden Stars), Olumakinde Talabi (3SC), Daniel Etor (Niger Tornadoes) and Nsube Aniezemba (Enyimba).
The team will play several test games in the coming days.