Onuoha sympathised with team-mate Danny Welbeck last week, when the striker made his England debut against Ghana, the country he is also qualified to play for.
Welbeck can still play for the Black Stars because last week's draw at Wembley was a friendly, rather than competitive, fixture.
It is a similar situation facing Onuoha. Nigeria are keen on the former England Under- 21 international playing for them.
But Onuoha wants the decision put on hold for a few years yet with his long term aim to play in the World Cup in 2014.
I didn't reject or accept the invitation from Nigeria when it came, said Onuoha. I left it in the background. Danny said that Ghana didn't actually try to call him up for that (England) game so there wasn't a decision really, it was a bit unfair on him.
I know how difficult it is to decide which country to play for. I haven't committed myself to anyone yet so it is clearly quite difficult.
I have had the question flying around in the last few years, but I don't think the time is right for me to make it.
Danny is the same. He has another four years, essentially, before he has to make that decision.
Onuoha has more immediate concerns to think about, with manager Steve Bruce expected to bring him back at right-back against West Bromwich Albion on Saturday.
Under the terms of his loan arrangement, the 24-year-old had to sit out Sunday's draining 5-0 defeat at Manchester City, the seventh game without a win and a defeat that leaves Sunderland six points above the relegation zone.
There are a lot of players thinking we need to get as many points as possible before the end of the season, he said. We are desperate for that first win. For me personally, my focus is on what is in front of us.
I feel more relaxed thinking about trying to catch someone rather than those trying to catch us.
Onuoha was an interested observer in the stands at Eastlands on Sunday, taking the opportunity to watch the two teams he is currently attached to.
Bruce would like to turn his loan move in to a permanent arrangement, but nothing is likely to be sorted until deep into the summer.
It's difficult to say I belong to City because I don't even have a (squad) number there,
he said. I definitely feel a part of this squad at Sunderland.
It has started to feel different as the season has gone on.
I did not really know what was going to happen when I first signed, but I can't make any decisions so I have just had to accept it.
I know there are a maximum of seven more games now for me here. At the end of the season I will sit back and think how this went.
Then I will start pre-season, if it is at City to begin with, and see how things go from there. Essentially I am still their player so I am in their hands.
Sunderland expect to today reveal the extent of the knee injury which ruled Fraizer Campbell out of the defeat at City.
He is due to see a specialist, weeks after resuming full training following a long layoff from knee surgery.
Bruce, meanwhile, has turned to former Gillingham team-mate Dean White to help him out on the scouting front.
The departure of Ricky Sbragia from his role as chief scout last week has left him restructuring his staff.
White, at the Riverside Stadium ten days ago to watch Middlesbrough against Watford alongside the Sunderland boss, will not be a direct replacement for Sbragia.
But White will be carrying out a number of scouting missions, and could be based in the south, where he lives and used to operate as Brighton's chief scout.