MOSCOW (Reuters) -A Ukrainian drone smashed into a building in central Moscow on Friday after Russian air defences shot it down, disrupting air traffic at all the civilian airports of the Russian capital, Russian officials said.

A Reuters witness who was in the area described hearing "a powerful explosion". Reuters images showed workers and emergency workers inspecting a damaged roof of a non-residential building which the drone hit.

The Russian defence ministry and Moscow Mayor Sergei Sobyanin said there were no casualties after air defences destroyed a drone which then fell on a non-residential building of Moscow's Expo Center complex in the early hours of Friday.

The Expo Center is a large spread of exhibition pavilions and multi-purpose halls, fewer than 5 kilometers (3.1 miles) away from the Kremlin.

"At about 4 am Moscow time, the Kyiv regime launched another terrorist attack using an unmanned aerial vehicle on objects located in Moscow and the Moscow region," the Russian defence ministry said.

There was no immediate comment from Kyiv.

Air-traffic was briefly suspended at four major airports around the capital - Vnukovo, Domodedovo, Sheremetyevo and Zhukovsky - though later they reopened.

Russia's air transport agency said seven flights were redirected to alternative airports.

Drone air strikes deep inside Russia have increased since a drone was destroyed over the Kremlin in early May. Civilian areas of the capital were hit later in May and a Moscow business district was targeted twice in three days earlier this month.

Both Ukraine and Russia deny targeting civilians and civilians infrastructure in the nearly 18-month war."

Ukraine typically does not comment on who is behind attacks on Russian territory, although officials have publicly expressed satisfaction over them.

The New York Times reported in May that United States intelligence agencies believed Ukrainian spies or military intelligence were behind the drone strike on the Kremlin.

Russia invaded Ukraine in February 2022, sparking a war that has sown devastation across swathes of eastern and southern Ukraine, killed or injured hundreds of thousands and triggered the biggest rupture in Russia's ties with the West since the 1962 Cuban Missile Crisis.

(Reporting by Reuters, Writing by Maria Tsvetkova, Lidia Kelly and Mrinmay Dey; Editing by Jacqueline Wong/Guy Faulconbridge)