Updated

Secretary of State John Kerry heads to talks in Asia trying to quash fears that the vaunted US refocus on the region is not serious as he puts a personal priority on peace in the Middle East.

Kerry plans to attend Southeast Asian talks in Brunei from Monday, which has become his unofficial deadline to wrap up his latest Middle East trip in which he is shuttling between Israeli and Palestinian leaders to revive peace talks.

Even in Brunei, his focus will not be solely on Asia as he is expected to meet Russian Foreign Minister Sergei Lavrov on tensions over the Syria war and the mysterious presence in Moscow of US intelligence leaker Edward Snowden.

Kerry has visited the Middle East five times in as many months. His second trip to Asia since taking office in February -- he earlier went to China, Japan and South Korea -- is again part of a larger tour.

Kerry dismissed suggestions he was uninterested in Asia, saying that he planned to travel "shortly" to Indonesia and Vietnam and believed in President Barack Obama's so-called "pivot" of putting more of a focus on Asia.

Kerry said that the United States has always been capable of "dealing with more than one crisis in more than one part of the planet at the same time".

"People should not think that, because we are trying to bring peace to an area that has been struggling for 30 years now under the yoke of conflict and dissension, that that means we can't also pay attention to these other issues," Kerry told Voice of America during his latest trip.

Diplomats and some analysts have voiced concern that the United States is shifting back to older priorities after the departure of Kerry's predecessor Hillary Clinton, who prided herself on paying attention to Asia.

Clinton sought to develop a broader relationship with a rising China and spearheaded US outreach to Myanmar, which has surprised even many critics by embracing democratic reforms in the past three years.

Clinton was the first secretary of state to visit all 10 members of the Association of Southeast Asian Nations, with her aides arguing that the previous administration of George W. Bush neglected the economically dynamic and mostly US-friendly bloc due to preoccupation with the Iraq and Afghanistan wars.

A senior US official acknowledged that Asian nations voiced doubts about the Asia commitment as Clinton left. But he said that at a substantive rather than symbolic level, the United States is stepping up spending on its Asia projects at a time of belt-tightening.

The official noted that Obama has welcomed to Washington in recent months the leaders of Japan, South Korea, Singapore, Brunei and -- for the first time in half a century -- Myanmar.

Asian nations that were concerned a few months ago were now asking "more of what we bring to the table than whether we are at the table," the official told AFP on condition of anonymity.

Some observers said it was natural that a new secretary of state would try to be different. Kerry may face fewer risks in delving into the Middle East as, unlike fellow former presidential candidate Clinton, he is virtually certain not to entertain future political ambitions.

Walter Lohman, a Southeast Asia specialist at the Heritage Foundation, a conservative US think tank, said that Asian nations ranked the Obama administration well for engagement but knew that the Middle East "has a way of dominating Americans' attention".

"There is some wariness of whether Asia is a priority for Kerry or whether he is going to try to make his personal mark elsewhere -- the Middle East or Europe," Lohman said.

Ernie Bower of the Centre for Strategic and International Studies said that Southeast Asian nations largely welcomed Kerry's visit on his recent tour to India, which has been seeking a bigger role in the region as China rises.

But Bower voiced particular concern about the delay of a visit to Indonesia, which Obama and Clinton identified as a priority due to its rapid transition to democracy and moderate form of Islam.

ASEAN nations expect some shift with the departure of Clinton and White House national security adviser Tom Donilon, who focused heavily on China, but largely believe that Obama is committed to the region, Bower said.

"Their analysis is that the chief desk officer for Asia is now President Barack Obama," Bower said.

"The good news is that you want the boss engaged. The bad news is that the bandwidth of the president of the United States, almost by definition, is going to be sporadic," he said.