Amid rumor of a possible month-end media event, Apple today announced that the iPhone 4S will be available in China and 21 additional countries on Friday, Jan. 13.

“Customer response to our products in China has been off the charts,” said Tim Cook, Apple CEO, in a statement. “With the launch in China next week, iPhone 4S will be available in over 90 countries, making this our fastest iPhone rollout ever.”

Beginning on Jan. 13, the 4S will be available in Anguilla, Antigua and Barbuda, Bolivia, Botswana, British Virgin Islands, Cameroon, Cayman Islands, Central African Republic, China, Dominica, Dominican Republic, Ecuador, Grenada, Guam, Guinea Conakry, Ivory Coast, Jamaica, Kenya, Madagascar, Mali, Mauritius, Niger, Senegal, St. Vincent and The Grenadines, Trinidad and Tobago, Turks and Caicos and Uganda.

Prices will be the same as in the United States. The iPhone 4S comes in either black or white for $199 for the 16GB model, $299 for the 32GB model and $399 for the 64GB model.

China has emerged as a major growth region for Apple in recent years. Greater China revenue has grown from 2 percent of Apple’s total revenue in 2009 to fully 16 percent in the fourth quarter of 2011. Apple now has more than 7,000 points of sale for the iPhone in Greater China.

“I’ve never seen a country with as many people rising into the middle class that aspire to buy products that Apple makes,” Cook said of China, according to a transcript of the company’s fourth-quarter earnings call posted on Seeking Alpha.