New York-headquartered Human Rights Watch and the Cairo Institute for Human Rights (CIHR) said that at the end of September there was a "wave" of arrests of people "peacefully celebrating or posting on social media" about the anniversary marking the creation of the Yemen Arab Republic.

The groups said the Iran-backed Huthis, who control vast swathes of Yemen including its capital Sanaa, had brought no charges against the protesters and "should immediately release all those who were detained solely for exercising their right to freedom of assembly and speech".

The Huthis have kidnapped, arbitrarily detained and tortured hundreds of civilians, including UN and NGO workers, since the start of Yemen's civil war in 2014, according to rights groups.