The boycott by the Indian and Canadian leaders is expected to sharpen the focus on demands by Western nations and rights activists that Sri Lanka account for thousands of civilians who are suspected of having died in the final months of a quarter-century civil war that ended in 2009 when government forces crushed separatist Tamil rebels.
India, which has a major interest in the issue because southern India is home to 60 million Tamils, has been urging Sri Lanka's government to resume negotiations with an ethnic Tamil party on increased local autonomy for Tamils. Canada also has a large number of Tamils who have sought asylum there because of ethnic conflict in their home country.
After the civil war, Sri Lankan President Mahinda Rajapaksa promised to allow a greater degree of autonomy in Tamil-majority regions in the north. However, he has been criticized by foreign countries and rights groups for failing to deliver on his promises.