He said soldiers have not been involved in any election campaigning and the military has been supporting reconstruction work in the north since the end of the country's quarter-century civil war in 2009.
Sri Lanka has faced rising international criticism for failing to demilitarize the north since government troops crushed separatist Tamil Tiger rebels, who were fighting to create a separate state for minority Tamils.
The ethnic Sinhalese-dominated government announced elections in the north amid intense international pressure that it share more powers with Tamils.
United Nations High Commissioner for Human Rights Navi Pillay, who recently visited Sri Lanka, said she heard complaints in the north of missing relatives in the war, intrusive military control of civilian affairs in education, agriculture and tourism, and acquisition of private land for military camps since the war.
The Tamil party was considered a proxy for the rebels during the war. Since their defeat it has abandoned separatism.