Asian stocks jumped Wednesday, boosted by announcements from China’s Ministry of Finance and Japanese Prime Minister Shinzo Abe.

In Japan, the main equity benchmark climbed by the most in more than seven years, shaking off unease about slowing growth in China.

A jump in U.S. stocks, which rallied overnight for their biggest one-day gain in two weeks, also helped investors in Asia overcome recent unease about China’s impact on the globe.

China’s Ministry of Finance lifted sentiment after it said it would speed up reform of the tax system, boost infrastructure spending and accelerate the use of the public-private-partnership model to support economic growth.

After that announcement, the Shanghai Composite Index SHCOMP, -1.28% closed up 2.3% while the Hang Seng Index HSI, -0.97% was trading up 4.2%, extending a rebound from late Tuesday. On Tuesday, Shanghai stocks rallied 2.9% and Hong Kong stocks gained 3.3%. Government-led buying supported a rally on the mainland, according to analysts.

“Any signal that [China’s] government is going to do more to support growth is going to help sentiment,” especially measures on top of monetary easing, said Bernard Aw, market analyst at IG. “The rebound in Chinese shares is across the board.”

In Japan, the Nikkei Stock Average NIK, -0.75% was back in positive territory for the year, closing up 7.7% Wednesday, after falling to a year-to-date loss Tuesday. Abe said the government plans to reduce the corporate tax rate by a cumulative 3.3 percentage points over two years, said an Australian Financial Review report.

The Nikkei scored its biggest daily percentage gain since October 2008, as well as the largest point gain since January 1994.

Despite the gains, many investors and analysts remain nervous. They remain anxious about the health of China and the global economy and are on alert ahead of next week’s meeting of the U.S. Federal Reserve, when the central bank could raise short-term interest rates for the first time in nearly a decade.

“The market focus isn’t [on Japan]. It’s on China and the U.S.,” said Hideyuki Ishiguro, senior strategist at Okasan Securities. “The Federal Open Market Committee meeting isn’t over yet.”

Data Tuesday showed China’s exports fell 5.5% in August from a year earlier in dollar terms after a drop of 8.3% in July, according to the General Administration of Customs. While analysts said the data weren’t surprising, the figures underscore how China’s economic slowdown is affecting trade, particularly for countries that focus their exports on Chinese demand.