A top advisor to Iran's hardline President Mahmoud Ahmadinejad on Thursday said Tehran will study the "constructive" offer for talks made by six world powers regarding its controversial nuclear drive. "It is a constructive proposal and shows a change of approach (from the world powers)," Ali Akbar Javanfekr told French news agency. "We hope that this proposal means a change of approach to a more realistic attitude. The Islamic Republic of Iran will examine (it) and give its response."