Berlin: Online whistleblower site Wikileaks says it is preparing to release more than 300,000 documents related to the Turkish government in the wake of last weekend's failed military coup that left hundreds dead, thousands injured and more than 7000 in custody.

"Get ready for a fight as we release 100k+ docs on #Turkey's political power structure," the organisation posted on Twitter on Monday evening.

Turkish President Tayyip Erdogan delivers a speech to his supporters in Istanbul after the failed coup. Credit:Getty Images

By Tuesday, it posted that its site was under sustained attack which it suggested was carried out by a "Turkish state power faction or its allies" - , drawing criticism from followers who accused the not-for-profit of teasing them with "trailers".