TBILISI -- The U.S. Embassy in Tbilisi says it is "disappointed" with the conviction and sentencing of Georgian opposition leader Gigi Ugulava in what the jailed politician has called a politically motivated case.

In a statement released on February 11, the embassy said it supports political dialogue between the South Caucasus nation’s ruling Georgia Dream party and opposition figures aimed at resolving disputes over the electoral system and other issues.

However, it said it was "disappointed that the timing and context of the conviction and sentencing of an opposition leader [on February 10] has put the dialogue at risk."

"An environment conducive to the successful continuation of the dialogue requires an independent, transparent judicial system free of political influence."

"We call on all sides to remain committed to the political dialogue, as well as further refinements to the electoral code, as the best way to create the conditions for free and fair elections," it added.

The statement comes after U.S. lawmakers recently expressed frustration over what they called "backsliding" on Georgia’s commitments to build democratic institutions in the country, a development that could potentially result in the United States reducing support to the Caucasus nation.

Georgian opposition parties have complained that the country's electoral system unfairly favors the ruling Georgian Dream party.

The country's Supreme Court sentenced Ugulava, who helped organize the protests, to three years and two months in prison on charges of misusing public funds while he was mayor of the capital.

It was Ugulava's second conviction on similar charges, in a case the opposition says is politically motivated.

A number of criminal cases have been opened against leaders of the opposition amid mass protests against tycoon Bidzina Ivanishvili's ruling Georgian Dream party and its government.

Dozens of former officials have been arrested on abuse-of-power and corruption charges since Georgian Dream came to power in 2012 after defeating then-President Mikheil Saakashvili's party in an election.

Ugulava, mayor of the capital from 2005 to 2013, was first sentenced to four-and-a-half-years in prison in September 2015 on similar offenses but was freed in January 2017 after a court reduced his sentence.

In 2018, Ugulava was sentenced again, to 15 months in prison, in the same case, but his sentence was considered to have been served.

The Supreme Court's February 10 ruling regards a new case of alleged misspending of funds, and the time he has already served will not count against it.

"This is a shameful decision made by the Ivanishvili regime," Tina Bokuchava, a leader the opposition United National Movement, told reporters.

Critics accuse Ivanishvili of running the country from behind the scenes.

Ugulava, one of the leaders of the European Georgian Party, said he had pleaded not guilty and that the verdict was a "legal farce."

"The fact is that the path chosen by the opposition frightens Ivanishvili," he told reporters before going to prison.

The United States and the European Union have called on the Georgian government, political parties, and civil society to engage in a "calm and respectful dialogue."

A group of 12 nongovernmental organizations in Georgia on February 11 called Ugulava's case "a continuation of political persecution against opponents."

"We call on the Georgian authorities, the ruling party, and the country's informal ruler -- Bidzina Ivanishvili -- to stop exercising selective justice against their opponents and dissenters, to promote a constructive resolution of the political crisis, and instead of party interests, prioritize the interests of the population and the country's development," a statement by the group said.

With reporting by Reuters