The United States is increasing pressure on Sri Lanka to investigate the deaths of thousands of civilians at the end of its civil war. Human rights groups contend a Sri Lankan government commission has demonstrated no intent of doing it.

The Senate passed a resolution this week urging an international probe into war crimes allegations. The State Department has not gone that far, but said Friday that pressure would increase if Sri Lanka should fail to carry out a proper investigation.

The long Sri Lankan conflict came to a bloody conclusion in 2009. Ethnic Sinhalese (SIN-ha-leeze)-dominated government forces cornered the last Tamil Tiger rebels on a sliver of land in the northeast of the island nation. Amnesty International estimates that 7,000 to 40,000 died in a five-month siege.