More than a million rare historic documents are believed to have been destroyed after a fire tore through one of Russia's largest university libraries, the Agence France-Presse reported.

The fire at Moscow's Institute of Scientific Information on Social Sciences broke out Friday and raged on until late Saturday, with some 200 firefighters battling the blaze. The exact toll of the damage has not yet been determined, but officials fear more than one million- about 15 percent - of the library's Italian, British and other texts dating back to the 1500s have perished.  

"It's a major loss for science," Russian Academy of Sciences President Vladimir Fortov said according to AFP. "This is the largest collection of its kind in the world, probably equivalent to the (United States) Library of Congress.

Other collections include one of the most elaborate Slavic language volumes in the world, philosophy texts and Marxism-Leninism manuscripts that arrived at the library from Germany as war trophies, according to The New York Times.

More than 21,500 square feet of the building was destroyed, AFP reported. Crews reportedly could not recover the books during the fire because the flames were too intense.

"One can find documents there that are impossible to find elsewhere, all the social sciences use this library," Fortov said.

"What happened here is reminiscent of Chernobyl," he added, referring to the disastrous nuclear accident of 1986.

At this time investigators believe an electrical short-circuit started the fire on the library's second floor. Arson is not believed to be the cause.