A mediation conducted by local tribal figures failed on Friday to release five United Nations staff kidnapped reportedly by gunmen in Yemen's turbulent southern province of Abyan, a government official said.

"Over the past few days, a high-ranking committee composed of local tribal figures conducted a series of negotiation rounds with an armed group for the aim of releasing the kidnapped UN staff in Abyan," the local government source said on condition of anonymity.

"The tribal mediation efforts ended in deadlock ... because the kidnappers demand a ransom of 5 million U.S. dollars ... while the UN officials and the local Yemeni authorities refuse to pay ransom for their release," he added.

There are attempts to form a new mediation committee to conduct another round of negotiations with the kidnappers during the upcoming days, according to the official.

Last Saturday, Russell Geekie, senior communications advisor to the UN resident and humanitarian coordinator for Yemen, confirmed that five UN staff members were kidnapped in Abyan "after having completed a field mission."

So far, no one has claimed responsibility for the kidnap, but local media indicated that the gunmen believed to be members of the Yemen-based al-Qaida branch intercepted a UN vehicle in Mudiyah district, east of Abyan.

The Yemen-based al-Qaida in the Arabian Peninsula (AQAP) network, which mostly operates in eastern and southern provinces, has been responsible for many high-profile attacks against security forces in the country.

The AQAP has exploited years of deadly conflict between the Yemeni government and Houthi militia to expand its presence in some key areas of the war-ravaged Arab country.