The revelation came after a news blackout on reporting the existence of the base was broken by two US newspapers. The blackout had been agreed by American media organisations and the Obama administration bceause of the national security issues involved.

The first pilotless CIA mission flown from the base killed Anwar al-Awlaki, a US-born cleric and senior figure in al-Qaeda in the Arabian Peninsula, and a deputy in September 2011, reports said.

Another Predator drone strike killed Awlaki’s 16-year-old son Abdulrahman weeks later, though US officials claimed in the Washington Post that he was not the target of the attack.

There have been at least 64 drone attacks on the unstable Arab state since 2002, though President Barack Obama dramatically escalated their frequency to an estimated one a week at times last year.

The disclosure of the drone airfield will embarrass the Saudi royal family, which still faces anger from powerful conservative clerics for allowing the US to establish military bases after the 1991 Gulf war.

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