"I have indicated that unless changes occur in Sri Lanka I will not be attending the Commonwealth summit there," Harper told parliament.
"I am concerned with further developments, since I made that statement, which are taking that country in a worse direction," he added.
Commonwealth Secretary-General Kamalesh Sharma has urged Canada to drop its threat to boycott November’s meeting in Sri Lanka over allegations of war crimes committed there during the civil war.
Instead, Canada stepped up pressure, reporting Sri Lanka to the Commonwealth for allegedly violating the organization’s democratic values by ignoring two court rulings and sacking Chief Justice Shirani Bandaranayake in January.
Bandaranayake had given rulings which were thought unfavorable to President Mahinda Rajapakse’s regime, which is also accused of failing to probe the war crimes allegations.