Japan's Shinsei Bank is considering proposing at an extraordinary shareholders meeting to be held as early as October measures to reject an unsolicited offer by online financial service firm SBI Holdings Inc. to take over the Tokyo-based bank, people close to the matter said Tuesday.

Shinsei Bank's board may meet this week and decide to seek shareholders' approval for an issuance of share warrants to resist SBI's plan to raise its stake in the bank to as high as 48 percent from the current 20 percent through a tender offer, they said.

File photo taken in May 2019 shows the building in which Shinsei Bank is headquartered in Tokyo. (Kyodo)

The bank is mulling issuing share warrants, the option to buy its new shares at a particular price, to existing shareholders other than SBI in an attempt to foil the proposed bid worth about 116 billion yen ($1.1 billion), they said.

SBI launched the tender offer running through Oct. 25 on Friday. The company, whose similar proposal in 2019 to raise its stake was rejected by Shinsei Bank, has been teaming up with regional banks to gain access to more retail investors and expand its online stock brokerage business.

SBI is the largest online stock broker in Japan in terms of the number of customer accounts.