BEIJING -- China's independently-developed AG600 large amphibious aircraft has conducted test flights over the sea, according to its developer Tuesday.

It represents a major step forward before the amphibious airplane model conducts its first taking off from the sea surface, which is planned within the year, said the state-owned plan maker Aviation Industry Corporation of China (AVIC).

Through the test flights, crew members confirmed and familiarized themselves with the airspace and marine environment for the upcoming test flight missions.

Codenamed "Kunlong," AG600 is designed to be the world's largest amphibious aircraft. Its development represents China's breakthrough in this field.

AG600 conducted its maiden flight in December 2017 and completed its first takeoff and landing on the water in October 2018.