A Saudi diplomat held hostage in Yemen since March appealed to King Abdullah to meet al Qaeda's demands to free detained women to ensure his release, according to a video recording posted online late on Wednesday.

It was at least the third video statement by Abdullah al-Khalidi since militants seized the Saudi vice consul in the southern Yemeni port city of Aden.

The United States and its Gulf Arab allies have been worried by the reach of al Qaeda and its allies in Yemen.

Khalidi, who appeared composed and wore a white robe and head dress, said Saudi authorities need to do all they could to ensure his freedom.

"I am a Saudi citizen who has served the Saudi government in more than one location. Don't I deserve to be released in exchange for setting some women free, just as Israel did when it freed more than 1,000 Palestinian prisoners in exchange for its prisoner held by Hamas," he said.

Israel released hundreds of Palestinian prisoners in October and December last year in a deal with Islamist group Hamas to free soldier Gilad Shalit after five years of captivity in the Gaza Strip.

Khalidi said Saudi authorities had met some of al Qaeda's demands and freed some of the detained women.

"I wish that the rest of the women in Saudi prisons be freed and that the remaining al Qaeda demands be met," Khalidi said.

"I appeal to the Custodian of the Two Holy Mosques, Crown Prince Salman bin Abdulaziz, Interior Minister Prince Ahmed bin Abdulaziz and Foreign Minister Prince Saud al-Faisal to help free me from captivity from al Qaeda and to meet the demands presented by the organisation to the government of Saudi Arabia," he added.

There was nothing in the footage to indicate when it was recorded and its authenticity could not be verified. Saudi officials were not immediately available to comment.

The Yemen-based Al Qaeda in the Arabian Peninsula is seen by US officials as the most dangerous offshoot of the global militant network.

A militant who claimed responsibility for Khalidi's abduction had threatened to kill the diplomat unless a ransom was paid and al Qaeda prisoners were freed from Saudi jails.

Last month, five al Qaeda-linked women detainees were freed by Saudi authorities. Interior Ministry spokesman Mansour al-Turki said at the time that the move was not linked to the demands of Khalidi's captors. - Reuters