Thousands of Russians have marched through Moscow and Saint Petersburg in memory of opposition politician Boris Nemtsov who was killed near the Kremlin a year ago.

According to the Russian interior ministry, about 7,500 people took part in the protests but Dazhd news agency put the figure closer to 20,000.

Nemtsov, a former deputy prime minister who became an outspoken critic of longtime President Vladimir Putin, was shot while walking across a bridge a short distance from the Kremlin and Saint Basil's Cathedral with his Ukrainian girlfriend.

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Some marchers carried Russian flags, placards, flowers and Nemtsov's portraits. Others chanted: "Russia will be free" and "Russia without Putin".

The march drew strong support from Nemtsov's political party, the People's Freedom Party, commonly known by its Russian acronym PARNAS.

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Mikhail Kasyanov, a former prime minister under Putin, marched at the front of the crowd.

Kasyanov is running for election to the federal parliament this year as a leader of PARNAS.

Maria Lipman, an independent political analyst, said the authorities only observed but did not intervene.

"It was a peaceful march, the police did not interfere and nobody was detained," she told Al Jazeera from Moscow.

"There were no speeches because the format of the event did not provide for speeches. The event was coordinated with authorities. It was tribute to a man who was killed last year in what was a purely political assassination."

Nemtsov's murder occurred just days before he was expected to lead a major opposition march and release a controversial report about alleged Russian military involvement in the Ukraine conflict.

In December, Russian Investigative Committee said it was charging five men with suspected contract killing.

Source: Al Jazeera and agencies