BRASILIA, July 6 (Reuters) - Brazilian hospital chain Mater Dei said on Tuesday its board has given the go ahead to buy a controlling stake in the Porto Dias hospital group in a deal involving 800 million reais ($154 million) and the issuance of shares.

Mater Dei will take a 70% stake in Porto Dias. It will issue 27.27 million shares, around 7.1% of the company's total share capital, and will have the option to buy the remaining 30%, it said in a securities filing.

Mater Dei shares closed on Tuesday at 16.60 reais.

The Porto Dias group operates in the northern region of the Brazil. (Reporting by Alberto Alerigi Jr. Writing by Jamie McGeever Editing by Chris Reese)