British Prime Minister David Cameron has warned against the economic risks of a so-called "Brexit" at a press conference after the G7 meeting in Japan. His remark has also been shared by the G7 leaders. The leaders issued a declaration on Friday that a UK exit from the EU poses a serious risk to growth. They say it would reverse the trend towards greater global trade and investment, and the jobs the UK creates. 

The comments highlight growing international alarm over the possibility of a "Brexit". UK voters are preparing for a referendum on June 23 to decide whether to leave the 28-country bloc. 

Cameron has been campaigning for Britain to stay in, with recent British polls suggesting a widening lead for supporters of continued EU membership. But the leave campaign is offering up stiff competition, with a number of high-profile supporters such as former London mayor Boris Johnson.