BEIJING, Nov. 16 (Xinhua) -- More than 20 senior security officials will attend the fifth Xiangshan Forum, slated for Nov. 20-22, said the organizer Sunday.

So far 48 countries and international organizations have confirmed they will send official delegations, said Pi Mingyong, secretary-general of the China Association for Military Science, which organizes the event.

The forum is expected to see delegates from 57 countries, Pi said.

The biennial event, which has been held since 2006 and focuses on security in the Asia-Pacific region, will be held annually starting this year.

To adapt to a changing security environment in the Asia-Pacific region and the need for security cooperation, the fifth forum will change from a pure academic forum to a high-end security and defense forum, said Yuan Zhiming, head of the forum's preparation team.