U.N. human rights experts have sent a letter to North Korea seeking more information about its decision to pardon an unspecified number of criminals against the state last year, voicing hope that it “could be a positive step.”

The five experts sent the inquiry to Pyongyang in November requesting detailed information about the scope of the amnesty announced as part of celebrations for the ruling party’s founding anniversary in October, according to the text of the letter released on Wednesday.

The letter was signed by Elizabeth Salmón, the U.N. special rapporteur on North Korean human rights; Matthew Gillett, vice-chair of