Facebook, the fast-growing social network, has taken a significant lead over MySpace in visitor numbers for the first time, according to one popular measure of internet traffic.

Facebook attracted more than 123m unique visitors in May, an increase of 162 per cent over the same period last year according to ComScore, a company that monitors websites. That compared with 114.6m unique visitors at MySpace, Facebook’s leading rival, whose traffic grew just 5 per cent during the same period, ComScore said.