Ali Mustafa said they had just found the remains of their relative Mohammed, whose body was found near a house in the village of Khan Khadim, some 30 km (18 miles) south of Sanaa.

“We still have no idea if the body really belongs to him or not,” he said, adding that the remains had been exposed to the elements. “We don’t know who these people are but we still need help from the international community.”

Witnesses said the men had disappeared on Thursday, as a curfew was imposed on Sanaa’s main square, in keeping with security directives after two of three men the rebels claim to be holding them were killed in a shootout with security forces.

The rebels are believed to have been hiding in a residential area for the past week. “When the police tried to storm the house they killed several men and injured several,” resident Fadel Hassan told Reuters.

The police chief for Sanaa said he believed the militants were hiding in the area in an attempt to disrupt ongoing police operations, and had not yet made a statement about the kidnapping of the two men.

Sanaa, a city that was seized by Sanaa-based insurgents in 2012, has been under an increasingly heavy security presence since last year, along with its southern neighbour southern port city Aden, also controlled by the rebels.

A Yemeni security official said the two men was believed to have been killed by security forces before their arrest. Security officials said the two men were from Khan Khadim and arrived in the city on an agricultural vehicle.

Yemen’s government denies any involvement in the kidnapping.

“The incident of kidnapped foreigners is a terrible shock to the country but this will not affect the stability of the country,” said army spokesman Brigadier General Ahmed Ali Abdullah.

The rebel commander Mohammed al-Assadi, who took the two men hostage, had earlier told a local radio station he believed the two men had been detained by a member of Ansarullah Bangla Team, a rival rebel group.