TORONTO — The United Church of Canada is asking Prime Minister Stephen Harper to formally intervene on behalf of Omar Khadr.

Khadr was captured in Afghanistan in July 2002 when he was 15 and later charged with throwing a grenade that killed a U.S. soldier in a firefight.

Khadr is expected to be tried as an adult at the U.S. prison camp in Guantanamo Bay, Cuba in May if defence motions to dismiss his case fail.

In its letter to Harper, the church says Canada should not remain silent in a precedent-setting prosecution of a child soldier for war crimes, "least of all when that child is a Canadian citizen."

Harper, however, has previously said Canada won't intervene in the trial of Khadr, who faces up to life in prison if convicted.

A pretrial hearing is scheduled for early February, when Khadr's lawyers will argue he should go free because trying him for crimes allegedly committed as a minor contravene international law.