* 1 pct point yield rise to trim BOJ's bond value by 24.6 trln yen
* BOJ's future exit won't trigger yield spike - Iwata
* Deputy gov: It's hard to lay out specific exit scenarios now (Adds quotes, detail)
By Leika Kihara
TOKYO, June 8 (Reuters) - Bank of Japan Deputy Governor Kikuo Iwata said on Thursday it would be hard for the central bank to release scenarios on how it could withdraw its monetary stimulus in the future.
"It would be difficult to lay out specific scenarios on an exit strategy now. Presenting several versions of it would confuse markets," Iwata told parliament, responding after a lawmaker said the BOJ should issue scenarios on how it would dial back its massive stimulus programme.
But he said the BOJ will keep looking for ways to better communicate to the public how the central bank's asset purchases could affect the central bank's financial health.
Iwata said that if long-term interest rates rise by 1 percentage point, it would shave 24.6 trillion yen ($223.9 billion) off the value of government bonds the central bank held as of March.
The loss would increase to 44.6 trillion yen if yields rose 2 percentage points and 88.3 trillion yen if they climbed by 5 percentage points, he said.
But Iwata stressed it was hard to calculate now how a withdrawal of stimulus could affect the BOJ's balance sheet, as that would depend on economic, price and market conditions at the time.
"When the timing for an exit comes, we will guide monetary policy appropriately so that long-term interest rates don't spike abruptly," he said.
After four years of aggressive asset purchases, the BOJ's balance sheet hit a milestone of 500 trillion yen, roughly the same size as that of the U.S. Federal Reserve.
Growing signs of life in Japan's economy have presented the BOJ with a fresh communications challenge, pushing it to be clearer on how it might dial back its stimulus - even though many analysts say such action remains a long way off.
$1 = 109.87 yen Reporting by Leika Kihara; Editing by Chris Gallagher and Richard Borsuk