COLOMBO- Sri Lanka's President on Monday named war veteran Shavendra Silva as its army chief, drawing sharp criticism from the United States over the appointment of an officer who has been accused of human rights violations.

Silva, 55, is credited with successfully leading an army division against dissident Tamil Tigers in the final phases of the island nation's 26-year-long civil war.

His victory, however, was highly controversial.

A United Nations panel has accused Silva's unit of shooting at unarmed rebels in the final week of the war which ended in 2009.

Silva, who joined the army in 1984 and was its chief of staff since January, has denied the accusations.

Washington expressed its disapproval of Silva's appointment in a strongly-worded statement.

"The allegations of gross human rights violations against him, documented by the United Nations and other organizations, are serious and credible," the U.S. Embassy in Colombo said in a statement.

"This appointment undermines Sri Lanka's international reputation and its commitments to promote justice and accountability, especially at a time when the need for reconciliation and social unity is paramount."

Silva was named head of the army after the previous chief Mahesh Senanayake's term ended on Sunday.

His appointment demonstrates a disregard for human rights, said civil society groups including the Centre for Policy Alternatives.

The Sri Lankan President's office and the military media unit did not immediately respond to requests for comment on the criticism.

(Reporting by Sankalp Phartiyal and Shihar Aneez, editing by Ed Osmond) ((sankalp.phartiyal@thomsonreuters.com;))