Top shareholders of Indonesia's PT Bank Muamalat aim to sell at least 51 per cent of the unlisted Islamic lender, in a deal that may be worth about $300 million, sources with knowledge of the plans said.

Bank Muamalat confirmed the sale process and said several investors had conducted due diligence to buy the stake.

Singapore's second-biggest lender Oversea-Chinese Banking Corp had looked at the bank in the first round, but is no longer interested, two sources told Reuters on Wednesday.

Bloomberg, which first reported the sale plan, said PT Bank Permata, a unit of Standard Chartered, Qatar Islamic Bank (QIB) and OCBC were among bidders.

Another banking source familiar with the matter said Qatar Islamic was the top contender for the stake purchase and that the Islamic lender had completed a due diligence process and presented an offer to Bank Muamalat.

The banker said the Indonesian lender may be valued at between $750 million and $1 billion, three to four times its book value of $250 million, while the Bloomberg report said the sale may value the bank at $600 million.

Qatar's largest investment bank QInvest is advising QIB on the sale, the source said.

Muamalat's total assets are 21.4 trillion rupiah ($2.5 billion). Its top three shareholders who are trying to sell the stake are Islamic Development Bank, Boubyan Bank Kuwait, and Saudi Arabia's Atwill Holdings, according to a source with direct knowledge of the deal.

These shareholders collectively control 75.7 per cent of the lender, according to its website.

Indonesia, the world's most populous Muslim nation, has a huge untapped market for Islamic banking, which local and international investors are trying to capture.

Qatar National Bank last year bought an 82 per cent stake in small local lender Bank Kesawan for $82 million.

Qatar's central bank asked conventional lenders to close down their Islamic operations in February.

Bank Danamon, controlled by Singapore state investor Temasek, and TPG-backed Bank Tabungan Pensiunan Nasional also plan to expand their sharia business.

Morgan Stanley is advising the shareholders on the sale, sources said, adding second-round bids are due in June.

Spokeswomen for OCBC and Morgan Stanley declined to comment.

Last year, Malaysian Islamic lender Bank Islam was trying to buy a stake in Bank Muamalat but dropped the plan earlier this year. – Reuters