A view shows the covered body of Boris Nemtsov, who was shot dead, in central Moscow February 28, 2015.
A view shows the covered body of Boris Nemtsov, who was shot dead, in central Moscow February 28, 2015.Reuters

A top Russian opposition leader and sharp critic of President Vladimir Putin, Boris Nemtsov, was shot dead early on Saturday in central Moscow. The incident occurred just a day before an opposition rally was scheduled to take place in the Russian capital.

The issue has sparked a debate over whether the current Kremlin government is somehow involved in the killing, especially because the 55-year-old staunch critic of the Moscow government had said in a recent interview that he feared Putin would have him killed as he is opposed to the war in Ukraine.

Nemtsov had told the Sobesednik magazine last month that he was "a bit" worried about being assassinated, adding: "Not as much as my mother, but still."

"If I were very fearful, I probably wouldn't head an opposition party. I probably wouldn't be involved in what I do," he had said.

Putin has himself, however, condemned the murder according to the Kremlin. The Russian president offered his condolences immediately after the incident came to light and called the killing a "provocation", ordering top law enforcement chiefs to personally oversee the investigation.

Spokesman for the President of the Russian Federation Dmitry Peskov said Nemtsov's murder "bears the hallmarks of a contract killing", adding that President Putin was assuming "personal control" of the investigation into the murder.

Nemtsov was reportedly shot four times from a passing car as he was walking by a bridge located just outside the Kremlin. He was with a female Ukrainian citizen, described as his "acquaintance", when an unidentified assailant from inside the car shot him dead from almost a point blank range. The woman in question escaped unhurt, Interior Ministry spokeswoman Yelena Alexeyeva said.

Meanwhile, US President Barack Obama condemned the "brutal murder" and called on the Russian government to conduct a quick, "impartial and transparent investigation".

"Nemtsov was a tireless advocate for his country, seeking for his fellow Russian citizens the rights to which all people are entitled," Obama said in a statement. "I admired Nemtsov's courageous dedication to the struggle against corruption in Russia and appreciated his willingness to share his candid views with me when we met in Moscow in 2009."

US Secretary of State John Kerry also described the late politician as someone who fought for a more democratic Russia and who had a vision for a "strong relationships between Russia and its neighbors and partners, including the United States."

Who is Boris Nemtsov?

A Russian statesman and liberal politician, Boris Nemtsov was widely known and referred to as a sharp critic of the Putin-led government and an equally vocal opponent of the ongoing Russian support for the Pro-Moscow separatists in Eastern Ukrine. Nemtsov has been documented in the country's history as someone who often condemned the government's inefficiency, corruption and foreign policies.

According to the Washington Post, he irked the Kremlin in 2013 by alleging that the government had stolen parts of the fund designated for the 2014 Winter Olympics in Sochi, which was his hometown.

Serving as deputy prime minister in the 1990s under then-President Boris Yletsin – the first elected president of the country – many had surmised that he would go one to take the top post one day.

When he served as the governor of one of Russia's biggest cities, Nizhny Novgorod, many analysts described him as an "economic reformer", the BBC reports.

Nemtsov is survived by his wife and four children.