Oktar said the giveaways - he estimated them at about 10,000 out of print runs of over 200,000 - were normal public relations funded by profits from sales of "The Atlas" and other books.
"That seems implausible - this book is expensive," said Taner Edis, a Turkish-American physicist whose 2007 book "An Illusion of Harmony" analysed Islam's approach to science. "And to my knowledge, it's not selling like hotcakes."
Edis doubted the rumours of funds from U.S. creationists, saying: "American creationists I talk to basically envy Harun Yahya's financial resources. If there were any fund flowing, it would be from Adnan Oktar to the creationists."
Saudi funding also seems unlikely because Oktar's message, while basically Sunni Muslim, mixes in Shi'ite and Sufi elements that clash with the kingdom's austere Wahhabi school of Islam.
"The Saudis don't like that," said an Istanbul Islam expert who asked not to be named because he feared litigation by the Harun Yahya group if quoted criticising it. He thought Oktar was mostly funded by a small group of affluent young Turks who make up the core group of his supporters.
JESUS RETURNS AS A MUSLIM
Long wary of the media and portrayed as the guru of a sect, Oktar has opened up recently, possibly because of a trial in Istanbul on charges of creating a criminal organisation. He was sentenced to three years in May but denies the charges and is appealing the verdict.
Oktar says the "Atlas of Creation" campaign and Harun Yahya publishing empire are part of his religious vision of the end of the world in which he plays a role hinted at in his pseudonym.
Harun is Arabic for Aaron, the brother of Moses. Yahya is Arabic for John - in this case, John the Baptist, he said.
"Harun was the helper of the prophet Moses. Yahya was also the helper of Jesus Christ," Oktar said. "When Jesus Christ comes to the world, we also would like to be helping him...You might say this is a prayer for that."
Oktar said Koran verses and sayings of the Prophet Mohammed about the end of the world revealed Jesus would return soon as a Muslim to help Islam's saviour, the Mahdi, defeat the Dajjal or Islamic Anti-Christ and establish Islam around the world.
"Our biggest project right now is to lay the grounds for the coming of Jesus Christ," he said. "We understand this is going to be in the next 20 to 25 years."
The idea of Jesus returning as a Muslim is standard Islamic teaching about the end of times. But Muslims normally stress the end times less than evangelical Christians do, and Oktar's focus on this has prompted rumours he thinks he is the Mahdi.
"I do not make such a claim," he said. "Because of parallels in what I have written and the hadith (sayings) of the Prophet Mohammad, some people have thought I could be him...but in Islam it is forbidden for me to make such a claim."
Asked if he planned another enormous book like "The Atlas", Oktar said he would simply continue to turn out anti-Darwin books. "I am preparing a book about skulls," he said. "I show skull fossils as evidence that there was no evolution."
