The United Nations has confirmed that 11 of its Yemeni employees have been detained by Houthi rebels and called for their immediate release.
UN spokesperson Stéphane Dujarric said the agency was pursuing all available channels to secure their unconditional release.
Houthi rebels in Yemen, who have declared their support to Palestinians in the Gaza Strip, have launched attacks on commercial shipping through the Red Sea corridor since Israel’s war on Hamas.
In its campaign to seek international attention, the group has attacked many employees of several international organisations.
Several charities and international humanitarian organisations have raised alarm over the detention of their staff members in Yemen in what appeared to be a coordinated campaign to crackdown on workers.
Mr Dujarric said: "We are very concerned about these developments, and we’re actively seeking clarification from the Houthi de facto authorities regarding the circumstances of these detentions and most importantly, to ensure the immediate access to those UN personnel."
"So I can further tell you that we’re pursuing all available channels to secure the safe and unconditional release of all of them as rapidly as possible."
The UN said nine men and two women have been detained. Six of them worked for the UN’s human rights agency, while others worked for its special envoy’s office, its development arm, Unicef, the World Food Program and Unesco.
The Mayyun Organization for Human Rights, which also reported UN staffers were held, named other aid groups whose employees were detained by the Houthis across four provinces that the Houthis hold – Amran, Hodeida, Saada, and Saana.
"We condemn in the strongest terms this dangerous escalation, which constitutes a violation of the privileges and immunities of United Nations employees granted to them under international law, and we consider it to be oppressive, totalitarian, blackmailing practices to obtain political and economic gains," the organization said in a statement.
Save the Children said it was "concerned of the whereabouts of one of our staff members in Yemen and doing everything we can to ensure his safety and well-being." The group declined to elaborate.
CARE International said one of its staffers had been detained without being given a reason.
"We are concerned about our colleague’s safety and are working to get more information in the coming hours and days," said Sulafah al-Shami, a CARE spokesperson. "Until then, we have extended our support to the family and share their hope for his speedy release."
An open online letter by activists, lawyers and others has called on Houthis to immediately release those detained, warning of further isolation of the country from the world.
Human Rights Watch, quoting family members of those detained, said "Houthi authorities have not revealed the locations of the people they detained or allowed them to communicate with their employers or families".
It comes as the Houthis are facing increasing financial pressure as well as air strikes by a US-led coalition against the attacks in the Red Sea.
The country recently introduced a new coin into Yemeni currency, the riyal, signalling the financial hardships. Yemen’s exiled government in Aden and other nations criticised the move, saying the Houthis are turning to counterfeiting.
Aden authorities also have demanded all banks move their headquarters there as a means to stop the worst slide ever in the riyal’s value and re-exert their control over the economy.
The armed rebel group, which seized the capital of Yemen, Sana’a, nearly a decade ago, controls the country’s capital and north-west. They have been fighting a Saudi-led coalition since then.
Additional reporting agencies
