The country's largest operator Advanced Info Service Pcl (AIS), second-ranked True Corp Pcl and Total Access Communication Pcl (DTAC) were allocated one 10-MHz block each on the 700-Mhz spectrum, said the National Broadcasting and Telecommunications Commission (NBTC).

Taking part in the 700-MHz auction has been set by the NBTC as a condition for the three operators to receive an extension to the payment period for their 900-MHz licences.

The extension would allow SingTel-owned AIS and True, which won licences in 2016 for about $2 billion each, to pay the remaining amount in six instalments until 2025, instead of the final instalment in 2020.

The announcements sent True shares up 4.7%, AIS up 1.5%, while DTAC's shares slipped 1.9%.

DTAC, owned by Norway's Telenor, won a spectrum licence for $1.2 billion last year, and could now pay in eight more instalments from next year to 2027, instead of the earlier deadline of 2022.

The government previously said payment extensions would support the rollout of 5G technology aimed for late 2020.

(Reporting by Chayut Setboonsarng, Panarat Thepgumpanat, Patpicha Tanakasempipat; editing by Gopakumar Warrier)