The Brussels-based Rezidor Hotel group said the assailants had "locked in" 140 guests and 30 employees in the Radisson Blu Hotel.
The men stormed the hotel on Friday morning shouting "Allahu Akbar" or "God is great" in Arabic before firing on the guards and taking hostages.
Special forces are carrying out an operation to rescue them - it's reported 80 people have already been freed.
Three people died when 10 gunmen attacked.
Revd George Obeng, pastor at the Lighthouse Chapel International, in Bamako told Premier's News Hour that Christians could be at risk: "We understand that some of the people released were made to recite part of the Koran before they were released - so there's a tension creeping up, because if you cannot recite the Koran, it means that you'll be held hostage."
The US and French embassies asked their citizens to take shelter where they are in Bamako.
"There a several kinds of people, airline officials, and business men - lots of different kinds of people - we always say it is a high class hotel, I think it's a three or four star hotel," said Revd George Obeng.
He told Premier that persecution against Christians is subtle: "It's the kind of situation where you are not really allowed to own property, you cannot rent easily places for worship - or even for habitation - so it's not direct but it's a certain subtle persecution that exists here."
Army commander Modibo Nama Traore said about 20 people had been released before troops launched the raid.
It was not immediately clear why the group was freed or how many remained held by the militants.
France's national security service said about 50 elite police troops are en route from Paris to Bamako.
A spokesman for the service said they are heading from two different units of special police forces trained for emergency situations.
French President Francois Hollande said France is ready to help Mali with all means necessary: "We should yet again stand firm and show our solidarity with a friendly country, Mali."
Mali's President Ibrahim Boubacar Keita has cut short his trip to Chad where he was attending a meeting of regional leaders.
Mali has had rising tensions since 2012 when a handful of jihadi groups seized the northern half of Mali and were ousted from cities and towns by a French military intervention.
About 1,000 French troops remain in the country.
Listen to Premier's Antony Bushfield speak to Revd George Obeng on Premier's News Hour here:
