Ait Mahdi, who leads a group for victims of a major 2023 earthquake, has been in detention since December 23 after criticising the kingdom's response to the disaster.

In January, a Marrakesh court had sentenced him to three months in jail for "defamation, insult and the publication of false allegations aimed at infringing on privacy".

On Tuesday, the Marrakesh appeals court "increased the sentence... to one year" behind bars, lawyer Mohamed El Ghalloussi told AFP, calling it a "very harsh and shocking" ruling.

Three other defendants in the case who had been initially acquitted were given four months in jail each for "insulting public officials", the lawyer said.

According to Ghalloussi, the case was based on "complaints from local officials following social media posts they considered offensive".

El Haouz province, to the south of Marrakesh, was one of the areas hit hardest by the 6.8 magnitude earthquake that struck the region in September 2023, killing close to 3,000 people and wounding 5,600.

It also destroyed around 60,000 homes in the High Atlas mountains, forcing many families to live in tents through the winter.

Ait Mahdi's group has campaigned for faster reconstruction and more aid to those affected.

The Moroccan authorities said in December they had issued 57,000 reconstruction permits and that more than 35,000 homes had been or were in the process of being rebuilt.

The authorities have put in place an $11 billion, five-year reconstruction and development plan for the six provinces hit by the disaster.