Costa Rica says China apologises for balloon 'incident' over its airspace

China apologised to Costa Rica for a balloon that flew over its territory, the Central American country's government said on Monday, after a separate suspected Chinese spy balloon travelling over the US sparked a major political and diplomatic spat.

A US military jet shot down that balloon just off its Atlantic coast on Saturday, after days of frenzied speculation over its mission, and on Monday President Joe Biden asserted that US-Sino relations were not weakened by the episode.

According to a brief statement from Costa Rica's foreign ministry, the Chinese government recognised that one of its balloons flew over Costa Rica, and China's embassy in San Jose "apologised for the incident," while insisting the balloon was focused on scientific research, mainly weather studies.

Costa Rican officials were told by Chinese officials the balloon flight path deviated from its original plan and it had a limited ability to correct the error, according to the statement.

A Chinese foreign ministry spokesman told reporters at a news conference in Beijing on Monday that the balloon spotted in Latin America was used for civilian purposes.

On Sunday, the head of Costa Rica's civil aviation agency said local officials had received reports of a balloon flying over the country last Thursday, after Colombia's military issued a statement on Saturday saying it had sighted an object similar to a balloon over its territory a day earlier.

Planes were notified at the time, but no further action was taken, according to the civil aviation director.