WASHINGTON • Admitted Russian agent Maria Butina has been sentenced to 18 months in prison after the Siberia native, her voice breaking with emotion, begged a judge for mercy and expressed remorse for conspiring with a Russian official to infiltrate a gun rights group and influence United States conservative activists and Republicans.

US District Court Judge Tanya Chutkan imposed a sentence on Friday that matched the prison term prosecutors requested and also agreed to have Butina, 30, deported back to Russia after she completes her incarceration.

The sentence includes the nine months Butina has already served in jail since her July arrest, meaning she has about nine more months behind bars.

Lawyers for Butina, a former graduate student at American University in Washington who publicly advocated for gun rights, had asked Judge Chutkan to impose a sentence of time served and let her return to Russia.

Clad in a green prison jumpsuit, Butina implored Judge Chutkan for leniency, calling her "dear judge".

"For all the international scandal my arrest has caused, I feel ashamed and embarrassed. My parents taught me the virtue of higher education, how to live life lawfully, and how to be good and kind to others," Butina said.

"I have three degrees, but now I'm a convicted felon with no job, no money and no freedom."

Butina pleaded guilty in December to one count of conspiring to act as a foreign agent, agreeing to cooperate with prosecutors.

The case marked another irritant in fraught relations between the US and Russia.

"This was no simple misunderstanding by an overeager foreign student," Judge Chutkan said before imposing the sentence.

Butina admitted to conspiring with a Russian official and two Americans - from 2015 until her arrest - to infiltrate the National Rifle Association, a group closely aligned with US conservatives and Republican politicians including President Donald Trump, and create unofficial lines of communication to try to shape Washington's policy towards Moscow.

Russian President Vladimir Putin yesterday slammed the jailing of Butina as "arbitrary", adding that he did not understand why she had been incarcerated.

"There is nothing we could accuse her of, but to make this case not look completely ridiculous, she was sentenced to 18 months in prison," he told journalists on the sidelines of a summit in Beijing.

Prosecutors said that while Butina did not engage in "traditional" spy craft, she worked behind the scenes to make inroads into conservative political circles and promote warmer US-Russia ties. She arranged dinners in Washington and New York and attended events to meet prominent politicians.

Mr Alexander Torshin, a deputy governor of Russia's central bank, was the Russian official mentioned in the case. Mr Torshin was not charged.

Butina's case was separate from Special Counsel Robert Mueller's investigation of Moscow's interference in the 2016 US election, which detailed numerous contacts between Mr Trump's campaign and Russia.

Her activities, though, occurred during the same period as the contacts investigated by Mr Mueller.

Until Friday, Butina had made no major public comments since her arrest. Her remarks ran counter to the Kremlin's account of Butina being forced by the US to falsely confess to the "ridiculous" charge of being a Russian agent.

"I destroyed my own life," Butina told the judge. "While I know I am not this evil person who has been depicted in the media, I am responsible for these consequences."

"If I had known to register as a foreign agent, I would have done so without delay," she added.

"I just didn't register because I didn't know to."

REUTERS, AGENCE FRANCE-PRESSE