SINGAPORE (BLOOMBERG) - Singapore Press Holdings and an arm of Keppel Corp are considering making a buyout offer for M1, Singapore's smallest wireless operator, people with knowledge of the matter said.

The companies are considering launching a general offer for shares they don't already own in M1, which has a market value of $1.51 billion, according to the people. They have approached M1's biggest shareholder, Malaysian carrier Axiata Group, about the potential transaction, the people said, asking not to be identified because the information is private.

A deal for M1 could be announced as soon as the next few days, the people said. Keppel Telecommunications & Transportation, a listed subsidiary of Keppel Corp, owns about 19.3 per cent of M1, while SPH holds nearly 13.5 per cent, data compiled by Bloomberg show. SPH also owns The Straits Times.

Shares of M1 and Keppel T&T have been halted since Monday, pending announcements. Keppel has approached Singapore Press Holdings to take part in a possible transaction regarding M1 shares, the newspaper publisher said in an exchange filing on Monday, without providing more details of the deal.

Axiata may decide to make its own offer for M1 if the price announced by SPH and Keppel is too low, two of the people said. In July last year, SPH and Keppel - together with Axiata - ended a strategic review of their stakes in the operator after potential suitors to buy the city-state's smallest cellular services provider dropped out.

Representatives for SPH, Keppel and M1 didn't immediately respond to requests for comment outside regular Asian business hours.

"Axiata is consistent in our publicly stated position that we will consider all viable and appropriate options that will enhance our own shareholders' value," the Malaysian carrier said in a statement, declining to comment further.