One of two suspects charged with the murder of Russian opposition politician Boris Nemtsov, Zaur Dadayev, confessed under duress, a member of Russia's Human Rights Council said.

Andrei Babushkin, who visited Mr Dadayev on Tuesday, said he saw "numerous wounds" on his body, suggesting he had been tortured.

The suspect himself said he was tied up for two days with a bag over his head.

He said he only confessed so a friend arrested with him would be freed.

"There are reasons to believe Zaur Dadayev confessed under torture," Babushkin said after a delegation visited the suspect in prison.

Dadayev told the visitors he was mistreated in the two days after his capture in Chechnya on Saturday.

He also said he confessed to make sure a friend who was arrested with him would be released.

He said he planned to tell the truth in court, but was never given a chance to speak.

The second man charged, Shagid Gubashev, said he was beaten by his interrogators and maintains his innocence.

Nemtsov, a former deputy prime minister and veteran liberal politician, was shot in the back as he was walking with his girlfriend within sight of the Kremlin on 27 February.