At a news conference in Brazil, U.S. Defense Secretary Leon Panetta urged North Korea not to engage in any

provocation that could increase instability, as speculation mounts about a possible third nuclear test.

(SOUNDBITE) (English)U.S. DEFENSE SECRETARY LEON PANETTA, SAYING:

"I again would strongly urge them not to engage in any kind of provocation - be it nuclear testing or any other act -

that would provide greater instability in a dangerous part of the world. I do not have any specific information as to whether or not

they will proceed or not with additional provocations at this time."

Sources told Reuters that North Korea has almost completed preparations for a third nuclear test, a move that will draw

further international condemnation following a failed rocket launch if it goes ahead

Deborah Lutterbeck, Reuters