The approval was confirmed on Monday by legal firm Allen & Overy.
Banpu has offered Hunnu $1.80 per share, which could value the company at $477 million.
The proposed transaction would give Banpu control of Hunnu’s many coking and thermal coal deposits in Mongolia, including the Tsant Uul project in the South Gobi coal province, which could be in production next year.
Banpu gained a 12.39% stake in Hunnu last March, making it Hunnu’s largest shareholder.
If the transaction is successful then Banpu will acquire the remaining 88% of Hunnu’s shares.
The Hunnu board has recommended that its shareholders accept Banpu’s proposal in the absence of a higher offer.
