Air Nigeria is supposed to be a joint venture between Nigeria Airways and Airwing Aerospace (UK), and there were indeed rumours that they were getting a 747 from SQ. But there has been much written in the Nigerian press regarding this company lately.
Here are some articles;
Background on the airline - http://www.kwenu.com/nigeria/airways/adeworan_disinfo.htm
Air Nigeria aircraft to arrive soon - http://www.nigeriasyt.com/aa17.htm
SQ denies involvement - http://www.nigeriasyt.com/c18.htm
Call for review of Air Nigeria - http://www.nigeriasyt.com/aa51.htm
It will be a while before Air Nigeria gets off the ground, and I don't think they will be with SQ aircraft as has been rumoured (the rumour put out by Airwing Aerospace mind you).