Associated Press/Andrew Harnik
U.S. Ambassador to Japan Caroline Kennedy arrives for a joint news conference with President Barack Obama and Japanese Prime Minister Shinzo Abe, Tuesday, April 28, 2015, in the Rose Garden of the White House in Washington.

WASHINGTON — An internal watchdog says senior staff at the U.S. Embassy in Japan, including Ambassador Caroline Kennedy, have used personal email accounts for official business. Some emails contained sensitive information.

The State Department's Office of Inspector General says it has identified instances where emails labeled "sensitive but unclassified" were sent from or received by personal email accounts.

It says department employees are expected to use approved, secure methods to transmit sensitive but unclassified information when available and practical.

The report on the embassy's operations was conducted between January and March.

Kennedy is the daughter of the late President John F. Kennedy.

The department is currently reviewing thousands of emails Hillary Rodham Clinton sent and received from a private email account while secretary of state. Clinton also used her own email server.