Japanese authorities warned against the yen's rise as the currency rallied broadly early in Asia on Monday following Friday's devastating earthquake and tsunami in Japan.

Finance Minister Yoshihiko Noda said he is closely watching yen moves, while one of his senior staff vowed to take decisive steps on currencies if needed, signaling Tokyo's readiness to step in to curb rapid yen rises.

The Japanese currency had risen sharply on Friday on talk of repatriation flows as the disaster unfolded. On Monday, the country was battling to prevent a nuclear catastrophe and to care for millions of people without power and water.

The dollar skidded to a low around 80.60 yen on trading platform EBS, compared with 81.87 yen late in New York on Friday, before quickly paring losses to last stand around 81.60.

At this stage, I'm closely watching, Noda told reporters when asked what the government would do in response to rises in the yen.

Noda's comments came after a senior finance ministry official said Japan is ready to act decisively on currencies when needed.

There is no change in our stance that we'll take decisive steps on foreign exchange when necessary, the official told reporters.

(Reporting by Tetsushi Kajimoto; Editing by Chris Gallagher)