The Kenyan foreign minister has told Al Jazeera that al-Qaeda is responsible for the ongoing siege of a mall in Nairobi that has killed at least 62 people.

In an exclusive interview on Monday, Amina Mohamed said al-Shabab was not acting alone and that it was part of an international terrorism campaign.

She told Al Jazeera's James Bays that about 20 gunmen and women were behind the attack, and that both the victims and perpetrators came from a variety of nationalities.

Al-Shabab and al-Qaeda announced their alliance in in February 2012, and Abu Omar, a Somali-a-based al-Shabab commander, confirmed in an interview with Al Jazeerathat his group is taking orders from al-Qaeda.

"Al-Qaeda are our leaders, they are our mentors, they are our leaders …and we are all engaged in a single conflict against an international Christian crusade and so we are partners in this," he said.

Meanwhile, a government spokesperson said that all of the hostages had been evacuated from the shopping mall.

At least three al-Shabab fighters have been killed and ten soldiers wounded in the military operation to end the standoff.

"Our special forces are inside the building checking the rooms. Obviously it's a very, very big building," said government spokesman Manoah Esipisu.

"We think that everyone, the hostages, have been evacuated, but we don't want to take any chances," he said. "The special forces are doing their job and yes, I think we are near the end."

"The special forces call this sanitising. It's a very complex and very delicate operation," he said, but said no resistance was being encountered.

"At the moment they have not met any resistance, but of course we are not ruling out the possibility that there are a couple of them hiding in a remote room or corner," he told the AFP news agency.

Al Jazeera's Mohamed Adow reported from Nairobi that security forces had given priority to rescuing as many hostages as possible and that it had pledged to continue its operations in Somalia against al-Shabab.

"Kenya went into Somalia in 2011 saying that al-Shabab had attacked Kenya and that they were not just going to fold their arms and wait," he said.

"Kenya went into Somalia to protect its own security … and now they will continue what they started in Somalia."

Al Jazeera's Peter Greste reported from the vicinity of the mall that at least ten people have been arrested in connection with this crisis.

Foreign Minister Mohamed said governments needed to communicate better and share resources in the same way that armed groups were doing.

“We must stay ahead of the curb in this war on terrorism,” she said. “We’re going to fight them relentlessly with the same amount of resources."

The United Nations Security Council condemned the attack "in the strongest possible terms," and reminded Kenya that any response must comply with international human rights law.

Source: Al Jazeera and agencies