A Russian court on Tuesday sentenced 11 people to terms including life in prison after finding them guilty of a deadly bomb attack on the Saint Petersburg metro in 2017.

Abror Azimov, a 29-year-old from Kyrgyzstan, was sentenced by a military court in Russia's second biggest city to life in prison for organising and participating in a terrorist group.

Ten other people who are also from Central Asia were sentenced to between 19 and 28 years in prison.

All had denied the charges, and many said they were tortured.

Shokhista Karimova, 48, pounded the glass of the courtroom cage and cried "let me go" after she was handed a 20-year term.

The bomb blast in April 2017 killed 15 people in the Saint Petersburg metro and wounded dozens more.

The alleged perpetrator, Akbarjon Djalilov, a 22-year-old from Kyrgyzstan, died in the attack.

Ten of the defendants were accused of acting as accomplices, notably by providing Djalilov with explosives and false documents.

The charges ranged from organising a terrorist group and perpetrating an "act of terror" to weapons trafficking and making explosive devices.

Critics of the case say the defendants' connection to the attack was not proven and some claimed they were framed by Russia's FSB security service.

Shokhista Karimova was sentenced to 20 years in prison for involvement in the 2017 Saint Petersburg metro bombing
Shokhista Karimova was sentenced to 20 years in prison for involvement in the 2017 Saint Petersburg metro bombing AFP / OLGA MALTSEVA

The father of Abror Azimov and his brother Akram Azimov told AFP the prosecution had "no kind of proof of guilt other than that beaten out of the defendants."

The father, Akhral Azimov, who lives in southern Kyrgyzstan, added that Akram, the older brother, was "abducted" by security officers from a hospital in Kyrgyzstan and handed over to Russia.

"Having beaten him up, they sent him to Moscow... the FSB put a bag over his head and took him to a secret FSB jail and beat him and tortured him with water until he confessed to being involved," he said.

A video circulated by security officers of Azimov's detention was staged, claimed the father, who had appealed to both the leaders of Russia and Kyrgyzstan.

Russia's Investigative Committee on Tuesday defended the case, saying the evidence against the defendants was "irrefutable".

The suspects had been arrested in different Russian cities and detained in Moscow before being transferred to Saint Petersburg for the trial.

The prosecution said the defendants formed two "terrorist cells" in Moscow and Saint Petersburg and helped Djalilov by wiring him money and providing the explosives.

Defence lawyers have pointed to numerous irregularities in the case, however, and claim that evidence was planted.

One defendant said last month that they had been framed by the FSB after it "missed the terrorist".

The bombing was claimed by an obscure group, the Imam Shamil Battalion, which experts say is linked to Al-Qaeda.