Western nations, led by the US are expected to move a UN resolution calling on accountability for alleged war crimes citing lack of action.
"People in our country who belong to all religions and speak different languages are moving together in unity and strength towards reconciliation and development," President Rapaksa said.
"With utmost goodwill I call upon all countries to join hands with us in the path to democracy, development, national freedom and the strengthening of human rights."
There had been concern of rising nationalism in Sri Lanka with attacks on Muslim and Christian places of worship and business, even after a 30-year war ended in 2009.
The full text of the speech is reproduced below:-
We have unfurled the National Flag today to mark the 66th anniversary of Independence, when the whole of Sri Lanka enjoys freedom.
History records that where we are gathered today has links to several important places of our independence.
Temples and monasteries dating