The Mig was being flown by anti Gadaffi forces, they have admitted the loss this morning.
From Wikipedia
Libya had 109 MiG 23 in service. Most are grounded. 2011 civil war in February and March: at least 4 captured by rebels in air base in Benghazi February and March 2011.[citation needed] Four captured by rebels at Tobruk air base.[24] Four captured by rebels in hangar at Misratah.[25] One captured by rebels at Al-Abrak.[26]
So how will the boys enforcing the No Fly Zone tell the difference between a MiG23 operated by the Rebels from that operated by Gadaffi's Forces? However, I suppose as it is supposed to be a
No Fly Zone it does not really matter both should not be in the air.