TOKYO (Kyodo) -- The Nikkei stock index surged 6 percent Tuesday morning to above the 33,000 line as expectations grew for progress in talks on U.S. tariffs after Japanese Prime Minister Shigeru Ishiba spoke with U.S. President Donald Trump by phone.

The 225-issue Nikkei Stock Average rose 1,894.08 points, or 6.08 percent, from Monday to 33,030.66, a day after losing 2,644.00 points, its third-highest point drop on record. The broader Topix index was up 149.64 points, or 6.54 percent, at 2,438.30.

The U.S. dollar rallied in Tokyo to above the 148 yen line, helping to boost gains by export-oriented issues, but it lost upward momentum and remained capped due to persistent uncertainty over the global economic impact of the U.S. tariffs, dealers said.

At noon, the dollar fetched 147.32-33 yen compared with 147.75-85 yen in New York and 145.79-80 yen in Tokyo at 5 p.m. Monday.

The euro was quoted at $1.0970-0973 and 161.61-67 yen against $1.0898-0908 and 161.14-24 yen in New York and $1.1001-1003 and 160.39-43 yen in Tokyo late Monday afternoon.

Tokyo stocks climbed across the board with the benchmark Nikkei index briefly gaining over 2,000 points, also helped by heavyweight chip issues that tracked steep gains by their U.S. counterparts on the Nasdaq index overnight, brokers said.

Despite the sharp rebound, investors were still concerned about the uncertain impact of U.S. tariff policies on the global economy.

"The surge seems to be nothing more than a brief rally" after the Nikkei index lost more than 4,500 points over the last three trading days, said Kazuo Kamitani, strategist at Nomura Securities Co.'s Investment Content Department.