CAIRO, November 4. /TASS/. An explosion of either fuel or a bomb might have caused the crash of the Russian A321 plane over Sinai, the Reuters news agency said on Wednesday citing sources close to investigation of the flight recorders.

"It is believed to be an explosion but what kind is not clear," the source said quoted by Reuters. "There is an examination of the sand at the crash site to try and determine if it was a bomb.".