The WikiLeaks website says it has begun publishing more than two million emails from Syrian government officials that would embarrass not only Damascus but also its opponents.
The whistleblowing website says the emails are from Syrian political figures, government ministries and companies, dating from August 2006 to March 2012.
It said the emails would shine a light on the inner workings of the Syrian government and economy, and also reveal how the West and Western companies say one thing and do another.
The material, which it calls 'The Syria Files', extends from the intimate correspondence of the most senior Baath party figures to records of financial transfers sent from Syrian ministries to other nations, WikiLeaks said.
The emails are in several languages and include 68,000 in Russian. Moscow is one of Syria's main arms suppliers.
Syrian opposition leaders and Western governments say more than 15,000 people have been killed in the 16-month revolt against President Bashar al-Assad.
The uprising started with peaceful pro-democracy protests in March 2011 but has turned into a something approaching a civil war as the government's crackdown triggered an armed uprising.
In 2010, WikiLeaks angered the US by publishing diplomatic cables that disclosed confidential information relating to the wars in Iraq and Afghanistan.