"The seriousness of the issue probably warrants travel, but to where in the region, I don't know," a State Department official told reporters, asking to not to be named.

"The signs are not encouraging ... It's hard to predict what they (North Korea) are going to do next," the official said.

IAEA chief Mohamed ElBaradei said earlier Monday that Pyongyang has asked the UN atomic watchdog agency to remove seals and cameras from North Korea's Yongbyon nuclear facility.

The request came three days after North Korea confirmed it was working to restart the reactor at Yongbyon and no longer wanted US concessions promised under a landmark agreement signed in June, in return for abandoning its nuclear program.

"I certainly wouldn't rule out any travel by officials to the region," the State Department official said, although he would not say whom Washington might designate to travel to Asia if crisis talks are called.