Ahmed Awad bin Mubarak (pictured), chief of staff to the Yemeni president, was abducted from the car he was traveling in by gunmen in the capital Sanaa on Saturday.
The Houthi group said the abduction was to stop him attending a meeting scheduled for the same day on the country's new draft constitution.
"Holding bin Mubarak will help block the plan to split Yemen into six provinces. This is a political division which is unacceptable for us," a Houthi leader, Ali al-Quhum, told news agency dpa.
The draft constitution reportedly includes plans for making Yemen a federal state consisting of six provinces. That's something the Houthis oppose as it would mean weakening the power they have gained in recent months.
The Houthis, who demand more rights for Yemen's Shiite Muslims, have claimed control over vast areas of territory and have overrun the capital Sanaa since September. Their expansion has brought them into further conflict with local Sunni tribes and also led to clashes with operatives from al Qaeda.
Bin Mubarak, a businessman-turned politician, was selected by President Abed Rabbo Mansour Hadi last year to be prime minister, but his nomination was derailed due to strong opposition from the Houthis.
The constitution is aimed toward resolving the deep regional, political and sectarian tensions in the country, which has been in violent political transition since former President Ali Abdullah Saleh was ousted in 2012 following widespread protests.
Yemen is also a stronghold of al Qaeda wing AQAP (al Qaeda in the Arabian Peninsula) – a terror organization which most recently made global headlines for claiming to be behind the Paris attack on the Charlie Hebdo magazine.
As well as al Qaeda, Yemen faces a secessionist movement in its south. The security situation in the country is of concern to both Western and Gulf Arab countries, as Yemen borders top oil exporter Saudi Arabia and the key Red Sea shipping route.
se/tj (dpa, AP, AFP, Reuters)