* To sell 450 million shares, or 17 pct stake
* To use money to fund early debt repayments
* Accelerated bookbuild could raise $300 million - banker (Adds shares, Mattress Firm cash needs)
JOHANNESBURG, March 13 (Reuters) - Crisis-hit South African retailer Steinhoff will sell part of its $800 million stake in KAP Industrial, it said on Tuesday, another step in its efforts to shore up its finances and pay down debt.
Steinhoff, which has more than 40 retail brands that include Conforama, Poundland and Mattress Firm, faced a fight for survival after admitting "accounting irregularities" in December, wiping about 85 percent off its market value and throwing it into a liquidity crisis.
The company has said it plans to raise around 2 billion euros ($2.47 billion) from the sale of non-core assets and the proceeds of debt repayments from its African unit Steinhoff Africa Retail to plug a hole in its balance sheet.
Steinhoff has already raised around $729 million from the sale of stakes in South African investment firm PSG Group, French online retailer Showroomprive.com, as well a property in Austria.
The KAP deal could bring in another $300 million, one banker said.
The company said it would sell 450 million shares, or a 17 percent stake, in KAP via an accelerated bookbuild - reducing its holding to 26 percent - to raise cash for repaying debt.
Steinhoff plans to use the proceeds to help fund the early repayment of its $1.3 billion South African bond, which would release money for Mattress Firm in the United States.
Mattress Firm, the largest speciality bedding retailer in the United States, needs a capital injection of around $200 million in the 2018 fiscal year, Steinhoff said in December.
Although the company has largely contained the short-term liquidity crisis in its European businesses, its working capital remains tight after it agreed with lenders it would not access undrawn credit facilities in exchange for creditors waiving due payments.
Steinhoff has already raised 7.1 billion rand from the sale of a stake in PSG Group.
It sold its 17 percent holding in online fashion retailer Showroomprive.com for 79 million euros ($97.4 million) and raised another 50 million euros from selling property in Austria.
KAP shares fell as much as 4 percent before recouping some losses to trade 2 percent lower at 8.33 rand by 0958 GMT, while Steinhoff was flat in Johannesburg and Frankfurt, where it has its primary listing.
Steinhoff said it would keep the 26 percent holding in KAP which it regards as a strategic investment.
"Steinhoff continues to view KAP as a compelling investment case, especially in view of recent events in South Africa and the prospect of improving economic conditions," Steinhoff said in a statement.
The election as president last month of Cyril Ramaphosa, who has promised to fight corruption and kickstart the economy, has lifted confidence among business leaders in Africa's most advanced economy.
KAP is a diversified industrial group selling everything from chemicals and auto components to mattresses.
Standard Bank and Investec are joint arrangers of the accelerated bookbuild. ($1 = 11.8355 rand) ($1 = 0.8112 euros) ($1 = 0.8105 euros) (Additional reporting by Maria Sheahan in Frankfurt Editing by Shri Navaratnam and Adrian Croft)