Two men, Anzor Gubashev and Zaur Dadayev, have been held in detention over the murder of Russian opposition politician​, ​Boris Nemtsov.

The head of Russia’s Federal Security Service, Alexander Bortnikov, announced this on state-owned television Channel One.

Mr. Bortnikov said Messrs Gubashev and Dadayev were arrested on Saturday and President Vladimir Putin had been informed of their detention.

Mr. Nemtsov, 55, a former deputy prime minister, was shot in the back four times on the night of February 27​ ​as he was walking on the street with his girlfriend. He was buried in Moscow on Tuesday.

Mr.​ Bortnikov gave no details of how and where the suspects were detained, in his brief statement. He however told Russian news agencies that the suspects were both from the Caucasus region.

The car allegedly used by the suspects was found and evidence gathered in the vehicle was used along with phone records to indentify the suspects, Interfax reported.

Mr. Putin has publicly condemned the murder and called for an end to “shameful” political killings in Russia. He said the murder was carried out close to Kremlin to embarrass his government and create the impression it was clamping down on the opposition.

However, leading opposition figure, Alexei Navalny, accused the Kremlin of ordering the assassination in order to cow the opposition amid Russia’s mounting economic problems.

Russian investigators have publicly offered multiple motives ranging from Mr. Nemtsov’s business dealings to his condemnation of the Charlie Hebdo attack in Paris.

Mr. Nemtsov was killed just days before a march he was organising against the war in Ukraine. He was reported to have been drafting a report expected to support his claim of Russian covert military involvement in the conflict.

Some 50,000 people attended a rally near the Kremlin in protest at his death on March 1 and thousands turned out to pay their respects on the day of his funeral.