Former Japanese Prime Minister Shinzo Abe has collapsed after he was shot at an event in the city of Nara, BBC reported.

According to news broadcaster NHK, Mr Abe was shot from the back and collapsed halfway during his speech, and appeared to be bleeding. His attacker was in custody, it added.

Ex-Tokyo governor Yoichi Masuzoe said in a tweet that Mr Abe was in a state of cardiopulmonary arrest, according to BBC.

Incidents of gun violence are rare in Japan, where handguns are banned.

The term cardiopulmonary arrest is often used in preliminary reports before a death is officially confirmed in Japan, reports say.