ISTANBUL (Turkey), August 21 (SeeNews) – Turkish state-owned oil and gas explorer and producer TPAO has signed a $1.0 billion (754 million euro) loan agreement with local Isbank [BIST:ISATR] and Vakifbank [BIST:VAKBN] to finance the purchase of an additional 10% stake in the Shah Deniz gas field in Azerbaijan, Turkish media reported on Thursday.