MOSCOW, Sept 23 (Reuters) - A coalition of defeated parliamentary candidates in Moscow who allege they were cheated of victory in a parliamentary election by a crooked online voting system said on Thursday they would try to overturn the results via lawsuits and public pressure. Some of the defeated candidates, most of whom are Communists, have called on voters to gather in Moscow on Saturday after eight parliamentary seats where the Communists had been ahead suddenly flipped to the ruling United Russia party once online voting results were added in. United Russia, which supports President Vladimir Putin, won a bigger than expected parliamentary majority despite unease over living standards, interim official results showed. read more The authorities have said Saturday"s planned meeting is illegal due to restrictions on public events related to COVID-19. The central election commission, which has said the vote was exceptionally clean and transparent, is due to formally approve the election results on Friday. The Kremlin said the election had been competitive, open and honest. In a statement published on Facebook on Thursday, the defeated candidates said they wanted the authorities to annul the results of electronic voting in Moscow and for the idea of electronic voting to be abandoned for future elections. "On Sept. 17-19 (when the election was held) millions of citizens of our country had their votes stolen," said the statement. "Therefore we, candidates from various political forces, have formed a committee to annul the electronic voting results." The statement was signed by Communist party candidates and candidates from the liberal Yabloko party, among others. At least two of them said police had come to their homes to warn them about the consequences of disturbing public order. The statement cited plans to hold a nationwide protest against what the committee believes is the rigged outcome of the election. No specific date was mentioned. "BLACK BOX" Jailed Kremlin critic Alexei Navalny had advised people to vote for some of the defeated candidates in a tactical voting campaign designed to try to thwart United Russia. Russian election officials, who promoted online voting as a transparent blockchain-based system, deny any fraud. They see online voting, which was used in a nationwide election for the first time, as a success which could be expanded ahead of a presidential election in 2024. "We need to use the practice as widely as possible," Kremlin spokesman Dmitry Peskov told reporters on Thursday. But critics said that, at least in Moscow, online voting turned out to be a "black box" with very limited access to the data even for election officials. Three members of an election commission set up for the Moscow online vote told Reuters that laptops designed for monitoring the voting process were cut off from the system when it was supposed to start the vote count. Given that the results of the count were delayed until the next morning, that raised their suspicions. Eventually, results arrived at the commission in PDF-files with no signs that they had any relation to actual voting, Anna Lobonok, an election commission member nominated by the Communist party, said. "I did not understand where the figures came from," she said, adding that calculations appear to have been made by technical specialists of a Moscow government department, which developed the online voting platform. Lobonok filed a complaint demanding the online voting results be annulled. A website set up for public monitoring of the online voting also stopped updating the data during the decryption of votes cast at night after the election.