By Hritam Mukherjee and Ashna Teresa Britto (Reuters) -UltraTech India's top cement maker will buy an 8.69% stake in Star Cement, it said on Friday, in a deal worth up to 8.51 billion rupees ($100 million) for a company that rival Adani Group was reportedly interested in acquiring.

Ambuja Cements, the cement unit of the group controlled by Indian billionaire Gautam Adani, approved a merger with two companies to expand amid a construction boom.

Leading cement producer UltraTech Cement on Friday announced to acquire a minority stake of 8.69 per cent from the promoters of Meghalaya-based Star Cement in a deal worth Rs 851 crore, further intensifying the competition with Adani Group entity Ambuja Cements.

India's UltraTech Cement will buy an 8.69% stake in Star Cement, it said on Friday, in a deal that could be valued at up to 8.51 billion rupees ($100 million) and firm its leading position in the sector.