'Resist urge to control e-cigarettes', WHO told
29 May 2014 Last updated at 06:51 BST
Fifty scientists from Europe, North America, Asia and Australia have signed a letter calling on the World Health Organization not to seek stringent controls on electronic cigarettes.
They say the products should instead be regarded as a "significant health innovation", but doctors' leaders say too little is known about the long-term effects.
Jane Dreaper reports.