Nov 2 (Reuters) - Russia said on Wednesday it would renew its participation in an agreement allowing Ukraine to export grain via the Black Sea, just four days after suspending its role in the deal.Moscow had pulled out at the weekend, saying it could not guarantee the safety of civilian ships crossing the Black Sea because of a drone attack on its fleet there.The U-turn followed a phone call between Russian President Vladimir Putin and Turkish President Tayyip Erdogan on Tuesday, and after consultations between their defence ministers."We did not bury this deal, but we did not expect Russia's return to it so soon either, as it was not very clear what kind of guarantees Russia could get and how quickly it would happen.Even after the call with the Turkish leader, the Kremlin had said Moscow would only consider resuming the agreement after a "detailed investigation" of a drone attack on Saturday against its Black Sea Fleet, which it accused Ukraine of carrying out with support from Britain."