Three Moroccan men have been arrested in connection with the bombing of a popular tourist cafe in Marrakech.

The suspects are reported to be “loyal” to al Qaeda, according to Moroccan police.

The bombing took place in Jamaa el-Fnaa, the city’s historic market square, last week. The attack killed 16 people include 11 foreign nationals – including one Briton, French, Dutch and Canadian tourists – and at least 23 others were injured by the explosion.

The nail bomb was detonated at lunchtime on 28 April. Moroccan authorities said the bomb had been set off remotely and not by a suicide bomber. A video released before the attack by al-Qaeda claimed responsibility.

Counter-terror investigators said a man disguised himself as a foreign visitor to plant the explosives. He had learned to make the devices on the internet, the statement said. It added that investigators found some explosive materials and tools that were discarded after the explosion.

“He made many attempts to go to such hot spots as Chechnya and Iraq before deciding to make this attack on Moroccan soil,” the statement from Moroccan officials said.

It did not provide any details about the other two suspects or about where the arrests had taken place

The attack is the worst in Morocco since 12 suicide bombers killed 33 people in co-ordinated strikes in Casablanca in 2003.

The latest attack was a blow to Morocco’s most important tourist city. Tourism is Morocco’s largest source of foreign currency and the second biggest employer after agriculture.

The attack have also added to the pressure of Morocco’s ruler, King Mohammed VI, who has promised a series of reforms in a bid to prevent uprising that have swept across North Africa.