China's foreign ministry has expressed "strong dissatisfaction and protest" against the United States' shooting down of its balloon.

A US military jet shot down the balloon, which China described as a civilian "unmanned airship," off the coast of South Carolina, on Saturday local time.

In a statement issued on Sunday, the ministry said that China had repeatedly told the United States that the aircraft had entered the US airspace by accident.

The ministry also said the use of force against the balloon was an "obvious overreaction" and violated international standard practices.

The statement added that China will "safeguard the legitimate rights and interests of relevant companies" and "reserves the right to make further necessary reaction."