Ukraine's spy chief has claimed that a coup to remove Russian President Vladimir Putin is "already underway" and that Moscow would lose the war by the end of this year.
Major General Kyrylo Budanov said he believed a turning point in the conflict will come later this summer and will eventually see Putin ousted from office, the Daily Mail reported.
"The breaking point will be in the second part of August," General Budanov told Sky News.
"Most of the active combat will have finished by the end of this year. It will eventually lead to the change of leadership of the Russian Federation. This process has already been launched.
"As a result, we will renew Ukrainian power in all our territories," he added.
It was also claimed by an unnamed Russian oligarch that Putin is "very ill with blood cancer", the Daily Mail reported.
The oligarch, who has close ties to the Kremlin, claimed a number of the health problems Putin is believed to be suffering from are linked to him having blood cancer.
General Budanov's comments are the most upbeat assessment given by any Ukrainian official since the war began on February 24.
But the Ukrainian head of military intelligence was one of the few top officials to correctly predict Russian troops and tanks would pour over the war-torn nation's borders to try to seize its territory.
However, in a rebuke to Russia's claims of military prowess, he branded Moscow's army "a horde of people with weapons", adding that "this highly publicised Russian power is a myth".
General Budanov also claimed Putin is in a "very bad psychological and physical condition", saying that he is suffering from cancer and other illnesses, the Daily Mail reported.
His health has been the subject of speculation this year, with his face becoming visibly puffy from what has been described as steroid use to treat one of his conditions.