By Maria Tsvetkova, Gleb Stolyarov and Anton Zverev
KOSTROMA, Russia (Reuters) - Russian President Vladimir Putin's party or candidates loyal to him have swept the board in local elections but in one region Reuters found signs of ballot stuffing, multiple voting and undue pressure on voters.
Public opinion, the Kremlin's control of the media and a dirty tricks campaign against an already enfeebled opposition ensured Putin's United Russia party would have triumphed anyway in Sunday's voting. Opinion polls show Putin is popular and there was no sign that ballot rigging was widespread.
But discrepancies witnessed in the Kostroma region northeast of Moscow highlight the obstacles faced by an opposition portrayed by Kremlin allies as fifth columnists in the pay of the United States or Ukraine.
Navigating an economic downturn compounded by a fall in oil prices and Western sanctions over the Ukraine crisis, the Kremlin cast Sunday's regional ballots as a dry-run for a nationwide parliamentary election next year.
Kostroma, a sprawling region of 670,000 people centered on a town of the same name almost 200 miles (320 km) from Moscow, was the only place where the opposition PARNAS party was allowed to run on Sunday.
PARNAS, co-founded by Boris Nemtsov, who was shot dead near the Kremlin in February, had needed to win at least 5 percent of votes to gain a foothold in the local parliament.
In the end, United Russia won 50.96 percent of the vote in Kostroma and PARNAS won just 2.28 percent.
"There were two main methods of falsifying the results," Leonid Volkov, a senior PARNAS activist, told Reuters.
"There was carousel voting, where people voted at several polling stations. And there was home voting when people were visited at home and guided how to vote."
Reuters reporters monitored voting at two polling stations - in the town of Kostroma itself, which is peppered with onion-domed churches, and in the village of Nikolskoye.
The monitoring team was in place without any breaks before polling stations opened until after they closed. The number of voters entering and the number of ballots cast was counted with a clicker of the kind used by airlines to count passengers.
In both cases, when the ballot boxes were opened, election officials said the number of ballots cast was higher than the number calculated by Reuters.
At the polling station in central Kostroma, Reuters put the final tally at 409 ballots but election officials put it at 434, or 6 percent higher. At Nikolskoye, the Reuters count was 531 but the officials tally was 547, or 3 percent higher.
When presented with Reuters' findings, the election commission in Kostroma said it had no immediate comment.
The discrepancies were not huge and it was a far cry from the scale of cheating alleged by the opposition in Russia's 2011 parliamentary election, which prompted mass protests. But if repeated in the about 700 other polling stations in the Kostroma region, they might have had a significant impact.
Asked why there was a discrepancy, Natalya Oshurkova, head of election commission 220 in Kostroma, said she did not know.
Svetlana Zvereva, her counterpart at Nikolskoye, initially came up with a turnout that varied from that of Reuters by one. She later said her initial count was only approximate and denied there were any ballots in the urn that were unaccounted for.
Reuters reporters witnessed several incidents which could explain where the extra votes came from.
In Nikolskoye, a man in a tracksuit and a woman in a blue dress were observed voting twice with an interval of 20 minutes. A woman was also seen stuffing a thick wad of voting slips into the ballot box.
There were also signs of coerced voting. When a group of 10-15 men in their 20s lined up in front of the electoral commission on Sunday, one said: "We were told to arrive here all at the same time for organized voting.”
He declined to give his name but said the group had come direct from a military hostel.
Later, an election official brought in 23 ballot papers, already filled in, from a military hospital nearby. Such "home voting" is legal but the opposition says it is often used to force people to vote for Kremlin candidates.
Pressure appeared to extend to soldiers' relatives too.
"That's it. We've come and voted. No one will say anything to our dad in his unit now," one woman said after voting.
PARNAS said it was largely denied access to media and that paid thugs disrupted its meetings. Police arrested its campaign manager, Andrei Pivovarov, accusing him of attempting to steal personal data - charges described by PARNAS as absurd.
On Sunday police also cordoned off a building being used by election observers funded by Mikhail Khodorkovsky, a Putin critic, saying they had to investigate a murder. Officials later said the report of a killing had proved groundless.
PARNAS was dogged by frequent allegations it was funded or advised by U.S. diplomats. When opposition leader Alexei Navalny visited Kostroma on Monday, unknown individuals plastered his car with stickers bearing the American flag.
Someone in Moscow hung a giant banner opposite the U.S. embassy portraying opposition leaders sitting on toilets with their trousers around their ankles and bore the words: "SORRY WE FAILED!"
The authorities say they followed the letter of electoral law in the registering of parties and that the elections were held in accordance with the constitution.
But Navalny likened the election to sitting down to a game of cards with swindlers when you know the rules of the game have been rigged in the swindlers' favor.
"We did not win any prize," he said. "But let's not give the swindlers what would be an important prize for them - our despondency."
(Writing by Andrew Osborn, Editing by Timothy Heritage)