* Nikkei ends 1.33 pct lower after brushing 10-day low
* Yen's steep surge vs dollar drives down exporters
* Fast Retailing hit by BOJ policy speculation
* BOJ speculation lifts banks; securities, insurers also up
By Shinichi Saoshiro
TOKYO, July 23 (Reuters) - Japan's Nikkei fell to a 10-day low on Monday, with exporters driven down by the yen's rally and index heavyweight Fast Retailing hit by speculation the Bank of Japan could wind back its exchange-traded fund purchases.
The Nikkei ended the day down 1.33 percent at 22,396.99 after going as low as 22,341.87, its weakest intraday level since July 13.
The dollar traded around 111.00 yen, having tumbled from the six-month peak above 113.00 scaled late last week after U.S. President Donald Trump said the strong greenback put his country at a disadvantage.
Accelerating the dollar's fall versus the yen were reports by Reuters and other media over the weekend that the BOJ could debate changes in its monetary policy at its upcoming meeting, with potential tweaks to its interest rate targets and stock-buying techniques on the table.
"The market is reacting as Trump's comments stopped the dollar's rise against the yen just as the U.S. currency was rallying. There is an impression that Trump speaks randomly, but the timing was exquisite," said Norihiro Fujito, senior investment strategist at Mitsubishi UFJ Morgan Stanley Securities.
"And the other factor weighing on stocks via the yen's weakening are the various media reports on the BOJ. The reports have stirred unrest in the market, which was caught off guard, thinking that the BOJ would not budge an inch from its current stance."
Exporters slid on the yen's appreciation. Toyota Motor Corp fell 1.73 percent, TDK Corp dropped 2.4 percent, Advantest Corp retreated 2.09 percent and Panasonic Corp shed 1.21 percent.
Fast Retailing Co, the operator of the Uniqlo clothing chain, slumped 5.72 percent, hurt by speculation that a potential tweak to the BOJ's monetary policy could put the shares at a disadvantage.
The central bank has been buying exchange-traded funds (ETFs) as part of its easing scheme. Speculation has risen in the market that potential policy tweaks could involve the BOJ concentrating its purchases from Nikkei-linked ETFs, which Fast Retailing has a heavy weighing in, to the broader Topix ETFs.
Losses in Topix stocks were less pronounced relative to the Nikkei. Topix ended the day 0.36 percent lower at 1,738.70.
Banks rallied on speculation that any tweaks to the BOJ's interest rate target could lift yields from previously low levels. Japan's 10-year bond yield jumped to a six-month peak on Monday following the BOJ-related reports.
Mitsubishi UFJ Financial Group Inc rose 3.64 percent, Mizuho Financial Group gained 2.73 percent, Sumitomo Mitsui Banking Corp climbed 2.79 percent and Shinsei Bank advanced 3.22 percent.
The banking sector was the biggest gainer of Tokyo's 33 sub-indexes.
Other finance-related sectors were also buoyant, with securities and insurance ending in positive territory.
Editing by Sam Holmes