With many polling stations closed, activists in the more than dozen insurgent-controlled towns were counting ballots behind closed doors yesterday. In the rebel hub of Donetsk, AFP and other media were barred from entering to observe the process.
The tallying rounded out a tense day in east Ukraine, where troops are waging an ongoing offensive against pro-Moscow gunmen.
Isolated violence flared in some towns. A freelance photographer working for AFP said he saw at least two people shot and badly wounded in the town of Krasnoarmiysk, apparently by a group of armed pro-Kiev militants.
The pro-Russian rebels put voter turnout at over 70 percent in the two provinces voting for self-rule: Donetsk and Lugansk, home to seven million of Ukraine's total population of 45 million.
With haphazard voter registration, no neutral monitors, incomplete electoral rolls, and no international backing at all -- not even from Russia -- that assertion lay open to challenge.
Swedish Foreign Minister Carl Bildt already challenged it, writing on his official twitter feed: "Figures from fake referendums in Eastern Ukraine likely to be fake. No way of knowing even turnout."
However rebel leaders hinted strongly that the poll results, expected to be announced today, were roundly in favour of making the two regions sovereign republics.
"Turnout was better than we expected," the rebel chief of the self-styled People's Republic of Donetsk, Denis Pushilin, said.
"Thanks to this referendum, we will be able to decide our own future," he said, adding that "we must make those occupying our land leave".
Vyacheslav Ponomaryov, the self-styled mayor of the flashpoint town of Slavyansk, boasted that the rebels could go on to organise other polls, including on whether to become part of Russia. "And I can even give you the figures if you want," he said.