TOKYO (Kyodo) -- The Nikkei stock index ended down nearly 4 percent Wednesday, retreating from the previous day's sharp rebound, as selling accelerated on fears of an economic slowdown following the United States imposition of additional country-specific tariffs, including on Japan.

The 225-issue Nikkei Stock Average tumbled 1,298.55 points, or 3.93 percent, from Tuesday to 31,714.03. The broader Topix index finished 82.69 points, or 3.40 percent, lower at 2,349.33.

All industry sectors lost ground on the top-tier Prime Market, with decliners led by nonferrous metal, insurance and mining issues.

The U.S. dollar hit a six-month low in the upper 144 yen range in Tokyo as the Japanese currency, seen as a safe-haven asset, was sought amid concern about a global economic slump triggered by U.S. tariff policy, dealers said.

At 5 p.m., the dollar fetched 145.53-54 yen compared with 146.21-31 yen in New York and 147.39-40 yen in Tokyo at 5 p.m. Tuesday.

The euro was quoted at $1.1014-1016 and 160.29-33 yen against $1.0951-0961 and 160.16-26 yen in New York and $1.0923-0924 and 161.00-04 yen in Tokyo late Tuesday afternoon.

The yield on the benchmark 10-year Japanese government bond ended at 1.270 percent, up 0.015 percentage point from Tuesday's close, after briefly rising to 1.355 percent, on speculation that the Japanese government will draw up a supplementary budget to deal with the impact of the aggressive tariff policies of the United States.

Traders also sold mainly super long-term government bonds on concern over the worsening financial situation.

On the stock market, losses widened after additional U.S. tariffs, including a 24 percent levy on Japan, took effect shortly after 1 p.m. Wednesday, with the Nikkei index briefly plunging more than 1,700 points, or 5 percent.

The tariffs were enforced at a time when the market was already reeling from trade tensions between the United States and China that intensified when Washington announced it would impose a 104 percent total tariff on Chinese imports as Beijing had not withdrawn its retaliatory measures.

"The imposition (of the tariffs) shows the United States maintains its hardline stance," said Maki Sawada, a strategist at the Investment Content Department of Nomura Securities Co. "The market was pressured by wariness and uncertainty" over how each country would respond.

The Nikkei index was dragged down by heavyweight semiconductor-related issues that tracked falls on their U.S. counterparts on the Nasdaq index overnight.

A stronger yen also led to selling of export-related shares, including some machinery and electronics companies that have strong sales in China, on concerns about an economic slowdown caused by further trade friction with the United States, brokers said.

The U.S. tariff policy has rattled the stock market. The Nikkei benchmark logged its third-largest point drop in history on Monday but rebounded the next day with its fourth-biggest point gain on record.

"The market faces the risk of declining further if a retaliatory battle seen between the United States and China spreads to other countries," said Masahiro Ichikawa, chief market strategist at Sumitomo Mitsui DS Asset Management Co.