Treasury chief George Osborne says Britain will undergo a "profound economic shock" should voters decide to leave the European Union.

Osborne, who is in China for a meeting of the Group of 20 leading economies, told the BBC that the recent weakness of the pound "reminds us all that this is not some political parlor game." The pound has hit seven-year lows as jittery investors react to uncertainty about the June 23 referendum on whether to remain in the 28-country bloc.

Osborne says that "leaving the EU would represent a profound economic shock for our country, for all of us."

The warning comes amid a report in the Financial Times that Osborne would urge other leaders attending the meeting in Shanghai to warn against a so-called British exit or Brexit.