The International Atomic Energy Agency's (IAEA) team at Ukraine's Zaporizhzhia Nuclear Power Plant (ZNPP) heard explosions and observed smoke coming from a nearby location, the UN nuclear watchdog said, with reports saying Russia launched a missile attack on Kiev.

"The IAEA team at Ukraine's Zaporizhzhia Nuclear Power Plant (ZNPP) heard explosions and saw smoke coming from a nearby location where the plant (sic) said one of its auxiliary facilities was attacked today (Saturday)," according to a statement by the IAEA on Saturday, citing the head of the watchdog, Rafael Grossi.

ZNPP officials informed the team that the facility, located 1,200 meters from the plant's perimeter, was hit by shelling and drone strikes starting at 9 am local time (0600GMT), coinciding with the time the team heard nearby military activity, it said.

Smoke from the area was still visible later in the afternoon, it stated.

The incident is the most recent in a series of events in recent weeks and months that underscore nuclear safety risks amid the military conflict at ZNPP, the statement highlighted.

"Any attack in the vicinity of a nuclear power plant – regardless of the intended target – poses potential risks also for nuclear safety and must be avoided. Once again, I call for maximum military restraint near nuclear facilities to prevent the continued risk of a nuclear accident," the statement quoted Grossi.

Later, Russia launched a missile attack on Kiev early on Sunday, the military administration of the Ukrainian capital said on its Telegram messaging app.

Witnesses heard a loud blast shaking the city soon after midnight on Sunday.