A knife-edge margin of 50.09% voted "yes" in Moldova's pivotal referendum on joining the European Union, partial results showed on Monday, after President Maia Sandu said Sunday's twin votes had been marred by "unprecedented" outside interference.

Moldova voted in favor of adding a path to the European Union to its constitution, and gave the incumbent president the most votes in elections Sunday, but neither result was the win leaders wanted.

Moldovans were evenly split on Monday amid final counting in a geopolitically momentous referendum on European Union accession with 50.08% in favor and 49.92% against, electoral authorities said.