Malian authorities arrested two people today suspected of links to an attack on a luxury hotel in the capital that killed 20 people.             

At least two armed men launched a dawn raid on the Radisson Blu hotel in Bamako last Friday, killing six Russians, three Chinese and an American among others, in the worst jihadist strike on the West African country in years.

The siege ended hours later when Malian commandos stormed the hotel and freed 170 hostages. Two attackers were killed.             

"There are two suspects arrested," said Amadou Sangho, a spokesman for the ministry, without naming them.

Three Islamist militant groups - al-Qaeda in the Islamic Maghreb, its splinter group al-Mourabitoun and Massina Liberation Front - have claimed the strike.

Security analysts say they could be collaborating.             

A source close to the investigation said the suspects had been brought in for interrogation, based on information found in one of the attackers' mobile phone.

One of them had been regularly in touch with one of the gunmen since August while another sent telephone credit to an attacker, he said.

"It's only after questioning that we will find out if the second suspect sells phone credit or is an accomplice," said the source, requesting anonymity.

The attack comes amid deteriorating security in the country just two years after a French-led military operation to scatter Islamist militants who briefly occupied the desert north.

French troops and a 10,000-strong UN peacekeeping force (MINUSMA) are struggling to stabilise the former French colony and strikes on both Malian and Western targets have spread further south and far beyond traditional militant strongholds.

The US embassy in Bamako has warned of the possibility of "further terrorist activity in the capital" and advised its citizens to avoid bars, restaurants and shopping centres.

Since the Radisson hotel attack, Malian forces have begun night patrols alongside UN forces and searched several private residences as part of a package of emergency measures.

Christophe Monbelli-Valloir, deputy police commissioner for MINUSMA, said a team from the FBI had arrived to help the Mali-led investigation.

Germany has said it is willing to send up to 650 soldiers to bolster the UN force which has yet to reach its full strength of 12,680.

It was not clear if the additional troops would expand the scope of the mission or help fill the current gap.