The buyout offer for Singapore's third-largest telco M1 has crossed a key threshold.

Keppel Corp and Singapore Press Holdings (SPH) now hold 90.15 per cent of M1's shares through their joint venture firm Konnectivity, according to an exchange filing yesterday.

"Strong support for the offer by shareholders has resulted in M1 ceasing to have at least 10 per cent of the total number of shares held by the public," said Keppel and SPH in the filing.

This means M1 will be delisted after the close of the voluntary general offer, as it no longer meets the free float requirement of the Singapore Exchange (SGX).

Konnectivity, which is majority owned by Keppel, and its concert parties currently control 835.1 million shares in M1.

Shareholders who may not want to hold shares in an unlisted company should consider accepting Konnectivity's offer of $2.06 per share by the extended deadline of March 18, said the exchange filing.

Keppel and SPH announced in December last year their "firm intention" to make a voluntary general offer of $2.06 per share for the remaining M1 shares that they do not own.

It was reported earlier this month that Keppel and SPH had obtained majority control of M1. This followed Axiata Group's acceptance of their joint offer for its entire stake of 28.6 per cent.

Axiata is a long-term shareholder of M1, which was listed on the SGX in 2002.

A consortium - comprising Keppel Group, SPH, Cable & Wireless and Hong Kong Telecom - formed M1 in 1994 to enter the mobile telecommunications market in Singapore.

The then fledgling telco obtained the licence in May 1995 to operate Singapore's second cellular telephone and radio paging services.