One of the three hopefuls is Regional Wireless Co, a joint venture between Australia's Telstra Corp and Richard Li's Pacific Century CyberWorks Ltd, which has already set about getting the financing for the buy.
On Friday, PCCW chairman Li had told reporters that he was in favor of bidding for M1, although he added that the decision would rest on Telstra, which owns 60 percent of Regional.
The newspapers quoted unidentified sources as saying the other two contenders are the Vodafone Group of Britain, and Malaysia's second-largest mobile operator, Maxis Communications.
However, neither the sellers nor the possible bidders would confirm the bids.
The Business Times cited an unidentified telecoms investor as saying that JP Morgan and Merrill Lynch, who are handling the sale of M1, have set an unofficial floor price of S$1.2 billion for the mobile company.
M1, with 800,000 subscribers, is estimated to be worth between S$2.5 billion and S$3 billion. It is held by Keppel T&T (35 percent), Singapore Press Holdings (35 percent), C&W (15 percent) and PCCW.