The head of Tunisia's National Heritage Institute urged authorities Tuesday to block the sale of royal artefacts at an auction in France, saying they were spirited out of the country.

More than 100 objects "of huge historical value were taken out of the country without any official authorisation in the second half of March, in the midst of the (coronavirus) lockdown", Faouzi Mahfoudh said.

"They don't belong to any state museum. It's private property," the head of the National Heritage Institute told AFP.

They include an ancient Koran which belonged to Mohamed el-Moncef Bey, one of the last representatives of the Husseinite monarchy that ruled Tunisia from 1705 until its independence from France in 1957, Mahfoudh said.

Also in the lot is the original copy of a reference book on the Husseinite monarchy written by 19th century Tunisian historian and politician Ahmed ibn Abi Dhiaf.

Among the 114 objects are ceremonial apparel from the start of the 20th century, religious manuscripts, poetry books and official correspondence.

They are due to go under the hammer in an online June 11 sale organised by the Paris-based Coutau-Bégarie auction house.

"The authorities must do what is needed to stop this sale because these objects have a priceless value and are part of the country's history," said Mahfoudh.

He said that authorities on Tuesday had launched an investigation to determine how the artefacts were smuggled out of Tunisia.

Mahfoudh said the National Heritage Institute had only found out on Sunday that the objects had left Tunisia without authorisation.

"I will not cede these objects to anyone for all the money in the world," Mahfoudh said.

The National Heritage Institute is also planning on submitting an official complaint to the state prosecutor, he said.