An even more deadly version of Swine flu could be on its way this Christmas experts have warned yesterday.

Scientists fear the H1N1 virus may come back this winter in a "dangerous" and more potent form. And that could send the death toll soaring for the bug, which has killed more than 60 people in Scotland and around 18,000 worldwide. [caption id="" align="alignleft" width="138" caption="Swine Flu medication"][/caption] Leading bacteriologist Prof Hugh Pennington said that every global flu epidemic has returned in a deadlier form. He said: "History shows that subsequent waves have been nastier and killed more people. "In 1918-19, when 50million died of H1N1, the second wave was much more serious than the first. "It is reasonable to expect swine flu to return this winter." The Aberdeen-based boffin added: "One possibility is we might get another virus which is a more lethal mutation." Next week the NHS will appeal to thousands of vulnerable Scots to get vaccinated against swine flu. A spokesman said: "It's expected that H1N1 will be the main flu virus circulating this winter. Most people will recover naturally within a week. "But those with health conditions, including heart and lung problems, are at an increased risk of experiencing serious complications. "These people, including children, are encouraged to receive vaccination from October 4." Last night Scottish Labour's public health spokesman Dr Richard Simpson said: "It would not be surprising to see a return of swine flu. "It's very important that people in target groups get vaccinated."