BANGKOK — Asian markets were mostly lower Wednesday following a hike in interest rates by China, a downgrade of Portugal's credit rating and signals from the Federal Reserve that it does not plan to expand its stimulus program.

Losses were limited though, as the first signs of progress appeared in Japan's frantic battle to contain a toxic radiation leak from a nuclear power plant that was thrown offline after a devastating earthquake and tsunami on March 11.

Japan's Nikkei 225 slipped 0.2 percent to 9,594.99, with major exporters losing ground amid interruptions in production following the quake that pummeled the country's industrial northeast. Sharp Corp. dropped 2.5 percent, Panasonic was down 1.8 percent, and Sony Corp. lost 1.6 percent.

Moody's Investors Service says it may downgrade its credit rating for Toyota Motor Corp., the world's No. 1 automaker, due to concern over suspended car production. Toyota's shares were down 0.2 percent.

South Korea's Kospi index fell slightly to 2,129.18, while Australia's S&P/ASX 200 lost 3.1 points to 4,897.00. Benchmarks in Malaysia, Indonesia, Vietnam and New Zealand were also lower.

Hong Kong's Hang Seng rose 0.2 percent to 24,196.92. Benchmarks in Taiwan and Singapore also were higher.

Late Tuesday, China's central bank raised key interest rates for the fourth time since October in an effort to dampen high inflation. The series of rate hikes reflects concerns about overheating and excess liquidity in the Chinese economy that are driving up prices, especially of food.

Beijing is using gradual hikes in interest rates and bank reserve levels to stanch a flood of lending that helped China rebound quickly from the global financial crisis but now is fueling price rises.

Meanwhile, Portugal's financial woes deepened after Moody's downgraded its credit rating for the second time in less than a month, further fueling fears the debt-laden country will have no option but to seek an international financial rescue package soon.

The Bank of Japan starts a two-day policy meeting Wednesday and investors will be looking to see if it enacts any further easing measures. The central bank has pumped billions of yen into the economy as it tries to keep liquidity flowing through the system in the wake of the disasters.

It has also received international support to stem the export-sapping appreciation of the yen. The dollar rose to 85.35 yen from 84.88 yen late Tuesday in New York. The euro rose to $1.4260 from $1.4245.

A rare bit of relief for quake-battered Japan came early Wednesday, when workers at Japan's tsunami-damaged Fukushima Dai-Ichi nuclear complex finally stemmed a tide of radiation that was pouring into the Pacific Ocean. But highly contaminated water continues to pool around the complex.

Wall Street's stock indexes were left little changed Tuesday after minutes from the most recent meeting of the Federal Reserve's policy committee showed few signs that the central bank plans to expand its stimulus program.

The minutes, from the Fed's meeting on March 15, confirmed that members of the central bank are split about whether it needs to tighten credit later this year to ward off inflation. All of the committee's members agreed that the economy is improving.

The Dow Jones industrial average fell less than 0.1 percent to 12,393.90. The S&P 500 index was essentially unchanged at 1,332.63. The Nasdaq composite gained 0.1 percent to 2,791.19.

Benchmark crude for May delivery lost 27 cents to $108.07 a barrel in electronic trading on the New York Mercantile Exchange. The contract rose $1.23 to settle at $108.34 a barrel on the New York Mercantile Exchange on Tuesday. (AP)