Opposition leaders in Ottawa and Nova Scotia are calling for further investigation into why the RCMP destroyed potential evidence in the criminal proceedings against a Halifax man who was wrongfully convicted of murder.

Federal NDP Leader Jagmeet Singh says an outside probe is needed to examine why RCMP destroyed an investigator's research on other suspects in the lead-up to Glen Assoun's unsuccessful 2006 appeal.

He calls techniques employed by police in the case "very concerning" and says they raise questions about how fairly accused are treated in our criminal justice system.

Assoun was convicted in 1999 of the stabbing death of Brenda Way in 1995 and spent 17 years in prison and four years on bail before being exonerated earlier this year after the federal Justice Department reviewed his case.

Green party Leader Elizabeth May says the need for an inquiry is heightened by the "disturbing" destruction of evidence prepared by an RCMP analyst in a unit that identified alternative suspects.

In addition, the leader of the provincial Progressive Conservative Party in Nova Scotia, Tim Houston, is calling for "an investigation of some sort," while Gary Burrill, the leader of the provincial NDP, is calling for an independent inquiry.

Conservative Leader Andrew Scheer's office said he declines comment as there may be pending legal action, while the federal justice minister referred questions to Public Safety Minister Ralph Goodale, who declined an interview.

Premier Stephen McNeil's office said he was unavailable for comment due to a busy schedule.