KYIV - Russia is resuming participation in a deal to free up grain exports from Ukraine because it realised the initiative would still work without Kremlin involvement, a senior Ukrainian official said on Wednesday.

Presidential adviser Mykhailo Podolyak said in a written statement to Reuters that Moscow's decision showed that Russian "blackmail" and "escalation and threats" fail when they meet a resolute response.

"One way or another, Russia, embarrassed, returned to the 'grain initiative' because it suddenly turned out that the grain corridor would work even without the Kremlin's participation," Podolyak said.

"This says only one thing: Russia is always inferior to those who are stronger, those who know how to take a blow, those who argue their position strongly."

Podolyak suggested the Kremlin had miscalculated when it suspended its participation in the deal on Saturday, saying it could not guarantee safety for civilian ships crossing the Black Sea because of an attack on its fleet there, part of which it said had originated from within the grains export corridor. Ukraine has said that was a false pretext.

"When you want to play blackmail, it is important not to outplay yourself," Podolyak said.

"Russia is used to constantly playing on escalation and threats. But if there is a firm position on the part of the other parties, the mediators, the guarantors, then it quickly becomes clear the threats are just formidable international PR."

Another senior Ukrainian official, who declined to be identified, told Reuters that Moscow's decision was mainly a result of Turkish pressure on Russia.

In a tweet, Infrastructure Minister Oleksandr Kubrakov also expressed gratitude for the roles played by Turkish President Tayyip Erdogan and U.N. Secretary-General Antonio Guterres.

(Reporting by Pavel Polityuk, Editing by Timothy Heritage)