A police sergeant in western Siberia says he and fellow officers have been ordered to use their own vehicles to guard President Vladimir Putin's billboards in an unprecedented operation to ward off "the protest-oriented population."

Adding to photos and eyewitness evidence from around Russia of such round-the-clock police surveillance, the officer says none of the other seven candidates' billboards is getting such treatment ahead of the March 18 election, which is expected to award Putin a fourth term in the Kremlin.

Last week, two campaign banners featuring enormous portraits of Putin in the Siberian city of Tomsk were defaced by vandals with paintball guns. One of the Putin images was left with a smear of blood-red paint dripping down from between his eyes.

There have been a number of similar incidents of vandalism targeting the incumbent's campaign banners, which bear his portrait and the slogan, "A strong president; a strong Russia."

In St. Petersburg last month, an unidentified man was filmed painting the word "liar" in large letters over a Putin billboard.

On the other side of the country, in Vladivostok, a Putin billboard was pelted with eggs. A similar incident happened in the Urals city of Orenburg.

Another billboard, in Serov, was reportedly hit with eggs overnight on February 11-12.

In response, authorities in cities across the country are reportedly ordering police to stand guard over Putin's advertisements 24 hours a day.

Police, however, are unwilling to acknowledge the use of such state resources or even the fact that there has been a vandalism problem targeting Putin.

Police protection of a Putin billboard in Novokuznetsk began after a vandal wrote "liar" on a billboard there.

"What are you photographing? Putin?" a police officer near the billboard asked an RFE/RL correspondent trying to document the scene. "Please do not photograph the president or our car. Show me your photos."

The officer then ordered the reporter to delete all the images.

A local blogger in Syktyvkar was also rebuffed when he tried to question a police officer parked next to a Putin billboard there.

On February 1, a website in Yakutsk published a police document assigning six officers to "precautionary action" with the name "BANNER." The officers were ordered to report with their own cars, a notebook, a flashlight, a whistle, a pencil, and a telephone for 24 hours of duty protecting Putin's billboards.

The police sergeant that RFE/RL managed to speak with in Kemerovo, in western Siberia, said of operation BANNER, "No one likes this work, but everyone is silent. Upsetting the bosses is a good way to get fired."

The police officer, who requested anonymity, said his unit was assigned to protect four Putin advertisements but he believed other officers had been assigned to the remaining ones. He added that only Putin's banners had been given security.

"They told us to protect them so that they were not damaged by the protest-oriented population," the sergeant said. "They told us that we need to be near the billboards, 'within eyesight.' They told us we can run the engine and the heater. After all, it is really cold."

He also confirmed that officers were expected to use their own cars for this work.

"They picked people precisely because they have their own cars," he said. "And they paired them with others who don't."

He said the department did not reimburse the officers for the use of their cars or the gasoline consumed.

The police officer said he had never heard of a similar operation in previous elections and had never previously been ordered to protect political billboards.

Asked whether he planned to vote for Putin, the officer said: "Of course not. I'm not going to vote."