Malian special forces have entered the Radisson Blu Hotel in the centre of Mali's capital, Bamako, where suspected Islamists are holding dozens of guests and staff hostage.

At least three people were killed after gunmen entered the hotel shooting, and shouting "God is great!" in Arabic.

The hotel is popular with expat workers.

A Malian army commander told the AP news agency that about 20 hostages have been freed.

Hostages able to recite verses of the Koran were being released, a security source has told Reuters news agency.

Six staff from Turkish Airlines are staying at the hotel, and a Chinese guest told China's state news agency Xinhua that he was among about seven Chinese tourists trapped there.

A French presidential source said French citizens were in the hotel, Reuters news agency reports.

In August, suspected Islamist gunmen killed 13 people, including five UN workers, during a hostage siege at a hotel in the central Malian town of Sevare.

France, the former colonial power in Mali, intervened in the country in January 2013 when al-Qaeda-linked militants threatened to march on Bamako after taking control of the north of the country.

I spoke to a gardener at the hotel who was sweeping the yard when the gunmen arrived.

"They were in car with a diplomatic licence plate. They were masked. At the gate of the hotel, the guard stopped them and they start firing. We fled," he said.

Another eyewitness said that it was difficult to say how many attackers there were, he said it could have between five and 13.

"They injured three security guards who were at the gate of the hotel," he said.

Popular Guinean singer Sekouba Bambino was among some guests who has managed to get out of the hotel. It is not clear how he escaped.

He said: "I woke up with the sounds of gunshots and for me it sounded like small bandits. After 20 or 30 minutes, I realised these are not just petty criminals."

Mali's President Ibrahim Boubacar Keita has cut short a trip to a regional summit in Chad.

"It's all happening on the seventh floor, jihadists are firing in the corridor," a security source told AFP.

Malian soldiers, police and special forces are on the scene along with some UN peacekeeping troops and French soldiers, the agency reports.

The US embassy in Bamako tweeted that all US citizens were asked "to shelter in place" and were "encouraged to contact their families".

Some reports say about 10 gunmen in total are involved in the attack.

The US Rezidor Hotel Group, which owns the Radisson Blu, said in a statement earlier that "two persons have locked in 140 guests and 30 employees".

The UN force in Mali took over responsibility for security in the country from French and African troops in July 2013, after the main towns in the north had been recaptured from the Islamist militants.