SAN FRANCISCO, Nov. 1 (Xinhua) -- Apple announced on Tuesday that its latest iPhone 4S smartphone will be available in China`s Hong Kong, South Korea and 13 additional countries next Friday.

Customers will be able to pre-order iPhone 4S beginning this Friday, the Cupertino, California-based company said in a statement.

The other 13 countries are Albania, Armenia, Bulgaria, El Salvador, Greece, Guatemala, Malta, Montenegro, New Zealand, Panama, Poland, Portugal and Romania.

So far, some owners have been complaining about the shorter battery life on their new iPhone 4S handsets. Apple is reportedly investigating the issue and has not made official comments yet.

The iPhone 4S looks the same as the previous iPhone 4 but has major hardware upgrade inside. Apple announced sales of more than four million units of iPhone 4S in the three days after its launch in the United States on Oct. 14.

The iPhone 4S now is available in 29 countries and is expected to arrive in stores in more than 70 countries by the end of this year.