KYIV, Aug 11 (Reuters) - Russia launched an air attack

on Kyiv, with air defence systems engaged in repelling the

strikes, Vitali Klitschko, mayor of the Ukrainian capital said

early on Sunday.

"Air defence units operating, air raid alert continues,"

Klitschko wrote on the Telegram messaging app.

Reuters witnesses said they heard at least two explosions in

what sounded like air defence units at work.

Kyiv, its surrounding region and all of eastern Ukraine were

under air raid alerts with threat of ballistic weapons being

launched at the country, Ukraine's air force said on Telegram