UPDATE 1-Market falls give mandate for action-U.S. Treasury

(Adds details from interview)

WASHINGTON, Oct 11 (Reuters) - Massive financial market selloffs in the past week reflect "enormous challenges" in the global economy and should prod leaders into action, a senior U.S. Treasury official said on Saturday.

"It gets everybody's attention and brings the leaders of the world together with a clear mandate to take urgent and decisive action," David McCormick, undersecretary for international affairs, told ABC's Good Morning America program.

McCormick declined to call the week's steepest fall on record a "crash," and said the U.S. government was taking action to deal with the crisis.

McCormick said there was an "absolute common view" among the G7 leaders of the need to act urgently and on the kinds of actions being taken, such as the $700 billion U.S. plan to acquire distressed financial assets and inject equity into banks.

He said details of the plan would be announced in the coming days and the plan would be executed in the coming weeks.

"When you think of something of this complexity, that pace is in some ways mind-blowing," he said. (Reporting by David Lawder, editing by Mike Peacock)