Foreign Office says Kremlin must track down those who orchestrated Boris Nemtsov's murder

The Foreign and Commonwealth Office is backing Boris Nemtsov’s family in their demands for a more complete investigation into his killing.

“Responsibility for his murder goes further than those already convicted, and we call on the Russian government to bring the perpetrators to account,” a Foreign Office spokesperson said.

On 27 February 2015, Nemtsov was shot and killed crossing the Bolshoy Moskvoretsky Bridge while walking home with Anna Duritskaya, his girlfriend, a 23-year-old Ukrainian model.

Five Chechen men were found guilty of the murder on 29 June and are due for sentencing next week.

Zaur Dadayev, a former Chechen soldier, was charged with shooting Nemtsov, while four other men acted as accomplices for supplying surveillance. All five have denied the charges and are appealing the verdict.

According to Reuters, the group were offered 15 million rubles (£195,000) for carrying out the assassination.

Those who organised the killing are still at large, said Nemtsov’s lawyers, who claim that "the masterminds are high-ranking people".

Vadim Prokhorov added: "It's the biggest crime of the century and yet they haven't identified the real organisers or those who ordered it."

Zhanna Nemtsova, the 55-year-old assassinated politician’s daughter, has called for Chechen leader Ramzan Kadyrov, to be questioned.

“In Russia and the world people are convinced the murder that was committed had a political subtext, but our investigators and court deny the obvious,” she wrote on Facebook. “At the same time, they haven’t been able to establish any sort of motive for the murder.”

Kadyrov has denied any connection with the killing but posted on his Instagram account that the gunman Dadayev as a "true patriot of Russia".

Nemtsov himself feared for his life in the days before his death, pointing the finger at the Russian president. 'I'm afraid Putin will kill me. I believe that he was the one who unleashed the war in the Ukraine. I couldn't dislike him more,' he said in an interview with Russia's Sobesednik news website.

On the second anniversary of Boris Nemtsov’s death in 2015, Sir Alan Duncan, Minister of State at the Foreign and Commonwealth Office said: “Boris Nemtsov was a man of great stature, who was admired in the UK for his essential and courageous work in promoting democracy.

“I urge the Russian government to ensure that all those responsible for this appalling crime are brought to justice. Like many in Russia and the international community, the UK government is continuing to follow developments closely."