Turkey denies it forced an Iranian cargo plane because of suspicions that it carried material for nuclear weapons to Syria. 

Turkey maintained that it occassionally conducts searches of Iranian planes entering its air space and that the downing of the plane was not unusual. However, it has not stated what the plane was carrying.

The cargo plane from Iran was ordered to land after it entered Turkish air space. Two F-16 fighter jets escorted the cargo plane to a southeastern Turkish airport, where it was searched for nuclear materials, according to the Doğan news agency.

Turkey has forged close ties with the Islamic Republic and Syria the past two years, discarding its former close relationship with Israel. Iran has been using various means to arm Syria, Iran and Hizbullah terrorists in Lebanon.

Syria previously has been suspected of building nuclear facilities, one of which was bombed by Israel while under construction four years ago.