Japan's Nikkei index, the regional heavyweight, slumped by 1.2 percent to 13,861.05. Hong Kong's Hang Seng index dipped 0.7 percent to 22,968.36. Losses weren't as steep on South Korea's Kospi, which fell 0.1 percent to 1,995.10.
Investor anxiety has risen as the U.S. budget impasse between Republicans and the White House drags on.
On Sunday, Republican House of Representatives Speaker John Boehner ruled out a vote on a straightforward bill to raise the government's borrowing authority without concessions from President Barack Obama before an Oct. 17 deadline, moving closer to the possibility of default.
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