Sri Lanka: UN says shelling 'killed civilians'

The UN has said widespread shelling by the Sri Lankan government killed most of the tens of thousands of civilians who died in the final months of the 25-year-long war, in 2009.

The report also accuses Tamil Tigers separatists of using civilians as human shields.

The UN is calling for an independent investigation into what it says could constitute war crimes.

Will Ross looks back at the history of the conflict.