KYIV, Ukraine — Six suspected spy balloons have been detected over the Ukrainian capital Kyiv, according to authorities.

The Ukrainian Air Force registered “around six hostile aerial targets” and shot some of them down, the Kyiv military administration announced on Telegram on Wednesday.

Initial findings indicate that the targets were balloons floating in the wind, which could be equipped with reflectors or intelligence equipment, the statement said.

It is possible that the Russians sent the balloons to detect Ukrainian anti-aircraft positions. The authorities are now examining the aircraft to establish their purpose, they said.

Ukraine has reported sightings of a series of airborne objects in recent days, while neighboring Moldova temporarily closed its airspace on Tuesday, reportedly due to a balloon that came from Ukraine and drifted on to Romania.

Moldova closed its airspace for more than three hours, citing security risks but without providing further information. The decision had been taken “to ensure the safety of civil aviation,” the Moldovan aviation authority said.

Initial reports suggested that a Russian drone had entered Moldova’s air space, before later reports said a spy balloon had flown initially over Ukraine, and then over Moldova.

Romanian flight control recorded the presence of a balloon over the south-east of the country at an altitude of 11,000 metres, roughly the cruising height of commercial flights.

There have been a spate of balloon sightings in recent weeks, causing aggravation in several continents.

Earlier this month, Washington shot down an airborne object it said was a surveillance balloon from China above US territorial waters, a step Beijing called an overreaction to what it claimed was a research aircraft.