* BOJ's ETF buy hopes curb early drops - traders
* Nikkei Volatility Index soars to 2-1/2-month high
* Showa Shell falls 3.8 percent
* Immediate support seen at 21,931.65, hit a month ago
By Ayai Tomisawa
TOKYO, June 28 (Reuters) - Japan's Nikkei ended flat but near one-month lows on Thursday, taking its cue from weakness on Wall Street as a simmering trade row between the United States and China hurt investor risk appetite.
The Nikkei eased 1.38 points to 22,270.39, its weakest closing since June 1. The index had dropped as much as 1 percent in early trade, before flirting with positive territory in the afternoon.
Meanwhile, the broader Topix dropped 0.3 percent to 1,727.00, the lowest closing level since mid-April.
Optimism that the Bank Of Japan would buy exchange-traded funds to support the market triggered futures buying, which curbed early declines, traders said.
The BOJ had bought 70.3 billion yen in ETFs for the past three days.
Thursday's losers included retailer and drugmaker stocks, with Takashimaya falling 1.3 percent, Astellas Pharma sliding 2.2 percent and Otsuka Holdings tumbling 2.9 percent.
As with many other markets, Japanese stocks have been hurt by worries that the global trade war between the United States and major countries, particularly China, will derail the global economy.
On Thursday, the Nikkei Volatility Index rose to 21.24, the highest since early April.
U.S. President Donald Trump said he will use a strengthened national security review panel to deal with potential threats from Chinese acquisitions of U.S. technology, instead of imposing China-specific restrictions, which initially helped U.S. shares.
But later on Wednesday, White House economic adviser Larry Kudlow said in an interview on Fox Business Network that Trump's announced plan did not indicate a softened stance on China.
"The market is cautiously monitoring new headlines about the trade war. The Nikkei will probably move in a fixed range for a while with a recent low served as an immediate support," said Shogo Maekawa, global market strategist at JPMorgan Asset Management.
The Nikkei's support level is seen at 21,931.65, an intraday level hit on May 30.
Showa Shell fell 3.8 percent after soaring to a record high the previous day on a media report that Idemitsu Kosan's founding family would drop its opposition to plans for a merger with its Japanese rival.
Showa Shell shares jumped as much as 19 percent to an intraday high of 1,900 yen on Wednesday before ending up 8.5 percent. (Editing by Jacqueline Wong)