Chewing tobacco and snuff are less dangerous than cigarettes but the smokeless products still raise the risk of oral cancer by 80 percent, the World Health Organization's cancer agency said on Tuesday.

The review of 11 studies worldwide showed people who chewed tobacco and used snuff also had a 60 percent higher risk of oesophagus and pancreatic cancer.

The researchers sought to quantify the risk of smokeless tobacco after a number of studies differed on just how dangerous the products were, said Paolo Boffetta, an epidemiologist at the WHO's International Agency for Research on Cancer.