US President Donald Trump hinted on Sunday that a completed agreement with Iran was close, but then backed away slightly and indicated that there was still some way to go.
Despite the fluctuations, the cheerful mood on the stock markets looks set to persist into Monday's opening trading session.
Japan's Nikkei 225 is up 2.9 percent at midday and the broader Topix is up 1.2 percent.
In China, Shenzhen rose 1.0 percent and Shanghai rose 0.8 percent.
Corrected: Removes incorrect price quotes from closed exchanges.
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