Academic access to Turkey's Ottoman archives, which could shed light on Armenian claims of a genocide, is being manipulated by the authorities.
The Turkish government has disputed motions in European parliaments that accuse Turkey of a genocide, in which up to 1.5 million people died between 1915 and 1923. It claims that the victims died in a civil war that also killed many Turks.
The Turkish authorities said there were no restrictions on access to the archives and researchers could have access. But statistics for access to the archives during the past decade have been disputed.
Turkish professor Halil Berktay, of Sabanci University, said: "Those controlling the archives approach access on the basis of extremely short-sighted national interest - what is good for Turkey. They give access to those people who they see as being friends of Turkey and refuse those who they see as hostile. We know that some archives relating to the period are completely sealed off."
International academics have also accused the Turkish authorities of hindering research into the dispute over the alleged genocide.
Rubyn Safrasayan, director of Turkish studies at Armenia's Yerevan University, said: "Researchers have been blocked from carrying out research even after being granted permission. We have scandalous cases where authorities physically prevented and tampered with foreign researchers' findings."
The controversy has led to several Turkish newspapers calling for change. One Turkish columnist said the "Turkish people have the right to know if what we are accused of actually happened".
The growing pressure has seen the Turkish army announce that it will open its archives, which date back to the Ottoman times. But such offers have been treated with scepticism.
Dr Safrasayan said: "We know that after the coup in Turkey during the 1980s, the military regime organised the destruction of many of most sensitive documents in the archives, especially those in relation to the genocide."
Much of the archive is unclassified. Researchers would have to sift through millions of documents, many of which are in poor condition.
Professor Berktay doubts whether incriminating documents will be found: "If you are looking for documentary evidence detailing direct orders from the pasha to secret organisations to kill and massacre Armenians, that I doubt exists, just as no document exists with Hitler's signature ordering the genocide. But we already have enough evidence to support those who claim the state organised the massacres."
Several of the country's most powerful families have been accused of building their fortunes on assets taken from the Armenian businessmen who perished. Historical proof, if found, could leave them open to massive financial claims, particularly in the United States.
An Armenian lawyer in Istanbul said: "I know that Armenians in the US are waiting to file cases for compensation against the Turkish government and individuals if the US recognises the genocide."