Families of victims who died in the events of September 11, 2001, joined commemorative ceremonies across Asia Wednesday.
Stock markets across Asia opened with brief observances and moments of silence.
Temples in Japan honored the victims killed in terrorist attacks on New York and Washington last year.
The U.S. embassy in Tokyo held a special memorial service.
But American embassies in Indonesia, Malaysia, Cambodia and Vietnam were closed amid security concerns.
Early morning commemorations started with the raising of the U.S. flag to half-staff in New Zealand. A chorus began Mozart's Requiem at 8:46 a.m., the time the first hijacked plane hit the World Trade Center one year ago.
Across Australia emergency workers paid homage to the firemen and police who lost their lives in rescue operations. In the Australian capital, religious leaders gathered to join relatives in a service remembering 10 Australian victims who perished in the attacks.
Australian Prime Minister John Howard remembered the impact of the day.
"A year ago today any sense of complacency that it could never happen here was swept away," he said. "These were attacks in the minds of Australians, not on distance unfamiliar places or cities. The cities of New York and Washington are very much the cities of our common culture."
South Korean President Kim Dae-jung sent a letter of condolence to President Bush in which he also promised continued support for the U.S. led global campaign against terrorism.