BRASILIA, Nov 12 (Reuters) - A consortium of Chinese companies signed a contract with the government of Brazil's Bahia state on Thursday to build a 12-kilometer (7.5-mile) bridge across the entrance of the bay opposite the city of Salvador.

The bridge to the island of Itaparica, slated to be the longest over water in Latin America, will take five years to build and cost 6.7 billion reais ($1.2 billion), Bahia officials said.

The consortium is made up of China Communications Construction Co Ltd, CCCC South America Regional Company and China Railway 20 Bureau Group Corporation, a unit of China Railway Construction Corp Ltd.

They will take one year to obtain licenses and prepare equipment needed to start building, the officials said.

"It is the biggest investment by a Chinese group in Brazil," Bahia Governor Rui Costa said at the signing.

The consortium's shareholders are the world's largest construction and infrastructure companies, he added.

(Reporting by Anthony Boadle; Editing by Richard Chang)