Millicom's major shareholder Atlas has raised its bid to buy out the telecom operator from the stock exchange.
Atlas, led by French billionaire Xavier Niel, is increasing its previous bid of 24 dollars per share to 25.75 dollars.
Niel, founder of the French telecom conglomerate Iliad, has previously owned 29 percent of the shares in Luxembourg-based Millicom, which was founded by the Stenbeck family's Kinnevik.
Millicom sells mobile services in Latin America under the brand Tigo and is listed on the Stockholm Stock Exchange.
The company rejected the previous bid and has until August 16 to respond to the offer.
On Friday, Millicom also released its report for the second quarter. The company reports revenue of 1.5 billion dollars, in line with forecasts, and an operating profit of 345 million dollars, which was higher than expected.
The share has risen by around 5 percent on the Stockholm stock exchange by lunchtime.