A group opposed to Chinese rule in the mainly Muslim region of Xinjiang has claimed responsibility for bombings around the country, saying they were part of a campaign against next month’s Beijing Olympics.

Chinese officials have repeatedly raised the possibility of a terrorist attack and used it to justify a security crackdown. However, the claims – brought to media attention by the US terrorism monitoring company IntelCenter – are certain to heighten security concerns around the Games, which open on August 8.