WASHINGTON (Reuters) - The United States urged continued humanitarian access to Nagorno-Karabakh on Tuesday as officials announced additional humanitarian assistance to address health care and other emergency needs.

The White House statement came as the death toll from an explosion and fire at a fuel depot in the breakaway enclave rose to 68, with a further 105 people missing and nearly 300 injured.

"We are saddened by the news that at least 68 people have been killed and hundreds injured in an explosion at a fuel depot in Nagorno-Karabakh and express deep sympathy to the residents of Nagorno-Karabakh and to all of those suffering," White House National Security Council spokeswoman Adrienne Watson said.

"We urge continued humanitarian access to Nagorno-Karabakh for all those in need."

On a visit to Armenia, Samantha Power, head of the U.S. Agency for International Development (USAID), said on Tuesday the United States would provide $11.5 million in humanitarian assistance.

The Armenians of Karabakh - part of Azerbaijan that had been beyond Baku's control since the dissolution of the Soviet Union - began fleeing this week after their forces were routed in a lightning operation by Azerbaijan's military.

(Reporting by Jasper Ward and Doina Chiacu; Editing by Leslie Adler and Marguerita Choy)