Australian Foreign Minister Kevin Rudd is heading to the United States on his first diplomatic mission since undergoing major heart surgery last month.

Rudd and Defense Minister Stephen Smith left Canberra Wednesday for two days of talks in San Francisco with their U.S. counterparts, Hillary Clinton and Leon Panetta. Rudd will also attend the United Nations General Assembly in New York, then head to Mexico for an official visit.

The 53-year-old Rudd underwent surgery in early August to replace a failing heart valve. He had similar surgery in 1993 to deal with heart problems caused by rheumatic fever when he was a child. He is returning to work comes two weeks ahead of schedule.

Rudd is under fire from opposition lawmakers over news reports that he has spent over $1 million traveling to more than 40 nations during his first nine months as foreign minister.

A spokesman for Rudd says traveling overseas is central to the job of any foreign minister and that he has been acting in pursuit of Australia's national interests.

Rudd was elected prime minister in 2007, but was ousted from the post last year in a Labor Party coup led by current Prime Minister Julia Gillard. But speculation is growing that he could be reinstated as Gillard's popularity continues to erode in opinion polls.