Six adults and eight children are among the latest cases of swine flu found in London, the south east and the east of England.
Ten of the new cases were found in London, meaning that the capital now has 57 of the 101 confirmed cases of swine flu in the UK so far.
Two new cases were found in returning travellers, while 11 cases involved people who had been in contact with those already identified with swine flu. Meanwhile, the source of the virus in one person remains unknown, said the Health Protection Agency.
The Foreign Office has updated its advice on travelling to Mexico, announcing that people should feel free to travel to the country. Before Friday, the recommendation was that people only visit if the journey was essential.
"This change follows a decline in new cases of swine flu reported in Mexico since a peak on 26 April and takes into account information and advice from a variety of sources, including the UK Health Protection Agency," said a spokesman.
World Health Organization officials have not issued any global travel restrictions, as tests on the virus have suggested that the strain is less virulent than initially feared.