Google is taking on internet telephone companies like Skype by allowing users to call from its free web-based email service.

For the moment only users in the US will be able to make calls from inside their Gmail account.

Phoning anywhere in the US and Canada will be free until the end of the year, while calls to the UK, France, China and Germany will cost 2 cents a minute.

Until now Google offered computer-to-computer voice and video chat services.