US President Joe Biden has commuted the sentences for most of the inmates on federal death row, converting them to life in prison without the possibility of parole.

Biden announced on Monday the reduction of sentences for 37 of the 40 federal death row inmates. The remaining three were convicted of terrorism and racial or religious hate-motivated mass murder.

Biden said in a statement, "I condemn these murderers, grieve for the victims of their despicable acts, and ache for all the families who have suffered unimaginable and irreparable loss."

He added: "I am more convinced than ever that we must stop the use of the death penalty at the federal level. In good conscience, I cannot stand back and let a new administration resume executions that I halted."

The move is believed to be in light of the inauguration next month of President-elect Donald Trump, who is a proponent of capital punishment.

The United States had suspended federal capital punishment for 17 years from 2003 in response to criticism that lethal injections cause unnecessary pain for those being executed.

Trump restarted it after he took office in 2017. Thirteen people on federal death row were executed during his first term.