KYIV, Oct 4 (Reuters) - Ukraine's navy said on Wednesday that 12 more cargo vessels were ready to enter a fledgling Black Sea shipping corridor on their way to Ukrainian ports, as Kyiv steps up a push to defy a de-facto Russian blockade on its vital sea exports.

Russia, which has a much more powerful and bigger naval fleet in the Black Sea, pulled out of a deal in July that had allowed wartime Ukraine to safely ship food products out through what is traditionally its main export corridor.

Ukraine responded by setting up a temporary "humanitarian corridor" for cargo vessels, and several ships have departed from Ukraine's Black Sea ports since.

"In total to enter the new corridor we have 12, and 10 to leave. That is as of now," Navy spokesperson Dmytro Pletenchuk told an online media briefing on Wednesday.

Those figures appeared to indicate an increase in the amount of shipping traffic set to use the corridor, although Pletenchuk did not say when the vessels were expected to sail.

He said Ukraine's defence forces were doing everything to ensure the safety of civilian ships in their territorial waters and that they were proceeding into the waters of Romania, Bulgaria and Turkey, all of which are NATO member countries. (Reporting by Olena Harmash; Writing by Tom Balmforth; Editing by Timothy Heritage and Alexander Smith)