* BOJ to boost corporate bond, commercial debt buying - sources

* BOJ may scrap bond-buying target to allow unlimited purchases

* Board to sharply cut growth, inflation forecasts - sources

* Policy decision expected 0300-400GMT Monday

* BOJ Governor Kuroda to hold briefing after shortened meeting

By Leika Kihara

TOKYO, April 27 (Reuters) - The Bank of Japan is expected to expand monetary stimulus on Monday for the second straight month to ease corporate funding strains and finance huge government spending aimed at combating the deepening economic fallout from the coronavirus pandemic.

Such a move would put the BOJ in line with other major central banks that have unleashed unprecedented amounts of monetary support amid the health crisis.

Sources have told Reuters the BOJ is likely to take further steps to ease funding strains for companies whose sales have collapsed, such as boosting purchases of corporate bonds and commercial debt.

The central bank may also clarify its commitment to buy unlimited amounts of government bonds by scrapping loose guidance to buy them at an annual pace of 80 trillion yen ($744 billion) per year, say sources familiar with its thinking.

Removing the guidance will be largely symbolic, they say. The BOJ has only purchased less than 20 trillion yen per year, as the bank's huge presence in the market allows it to control yields with fewer purchases.

"Still, it's something the BOJ could contemplate," one of the sources said. "By showing its resolve to buy bonds aggressively, the BOJ can send a message it is working closely with the government by keeping borrowing costs ultra-low," the source said, a view echoed by another source.

At the meeting on Monday cut short by a day as a precaution against the spread of the pandemic, the BOJ is widely expected to keep its interest rate targets unchanged.

Under a policy dubbed yield curve control, the BOJ targets short-term interest rates at -0.1% and 10-year bond yields around 0%. It also buys government bonds and risky assets to pump money aggressively into the economy.

FUNDING STRAINS REMAIN

The BOJ's rate review precedes those this week by the Federal Reserve and the European Central Bank, which have sailed into uncharted territories to keep their economies afloat.

Corporate funding costs have crept up in Japan despite the BOJ's decision last month to boost risky asset buying and create a loan programme to assist funding of firms hit by the pandemic.

Among the measures taken in March were a pledge for the BOJ to increase purchases of corporate bonds and commercial debt by 2 trillion yen.