The head of the US space agency NASA has expressed concern about China's space development, saying that Chinese officials are very secretive and lack transparency.

NASA Administrator Bill Nelson made the remarks in an interview with NHK in Tokyo on Monday.

On the state of China's space development, Nelson said, "They have accomplished many things within the last 10 years, and they seem to be very good."

But he expressed concern about China's desire to lay claim to the South Pole of the moon. He said knowing the history of China's moves, "They would go to the South Pole, where we think the resources are, and say this is our territory." Nelson stressed that dialogue with China is essential.

He referred to China's space station project, in which the debris of a booster rocket threatened to fall to Earth two years ago. He called the Chinese officials "very secretive," because they refused to tell where the booster was going to come down.

He added that China is going to need to establish some cooperation with the United States, but to this point, it has been unwilling to do so.

The NASA chief also spoke about the Artemis program, which is aimed at sending astronauts to the moon for the first time since the Apollo project from 1969 to 1972.

Nelson described space as "our future" and "an area of great exploration." He said the Artemis mission is to go back to the moon to stay. He added, "We are going to learn to live, to work, to invent, to create, to prepare to go to Mars with humans.

Nelson also stressed the importance of collaboration with Japan in space exploration and research. He called Japan a major friend and strategic partner for the United States.

He specifically mentioned a lunar rover that Japan will build. He said it will be an enclosed, inhabitable rover that will allow the astronauts to take off their spacesuits and move around the moon in a breathable atmosphere.

Nelson assumed his post at NASA in May 2021 after representing Florida for many years as both a Senator and Representative in the US Congress. He was involved in space experiments on board the Space Shuttle in 1986.