Nigeria manager Stephen Keshi told reporters: "We are not part of this, we do not have interests in this. We are here to play football and that's it.
"If they want to investigate it whenever they want, that's their problem. We don't know anything about this stuff."
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Some 66 people have been killed after the plane they were travelling on crashed in southern Iran.
The letter calls for an end to harassment, abuse, and impunity in a world "ripe for change".
Police say that anyone who sees Whitehouse should not approach him, but instead call them on 999 and quote incident 23 of 18 February.