US authorities have failed to adequately monitor weapons sales to Gulf countries criticized for dismal rights records or recent security crackdowns on protesters, a government audit said Friday.

The Government Accountability Office pointed to "gaps" in how the State Department and the Pentagon monitor military equipment, including sensitive technology, after it is sold.

Rising tensions in the Middle East and North Africa between long-standing regimes and protesters seeking their removal triggered concern from government auditors, especially ahead of a looming $53 million arms deal with Bahrain.

While the State Department has vetted hundreds of individuals and units due to receive US-funded training in the Gulf to make sure the equipment will not be used for rights abuses, it has not done so for $188 million in assets due to reach Oman and Bahrain, the GAO said.

"Such vetting is especially critical given Bahrain's use of its security forces to quell public demonstrations since Spring 2011," it said, noting the lapses mean that sensitive technology like night vision devices are left "prone to diversion."

Earlier this year, Bahrain's Sunni monarchy crushed pro-democracy protests, spearheaded by the majority Shiites, with the help of troops from other Arab states in the Gulf, led by Saudi Arabia.

Twenty-four people died during the month-long crackdown, according to official figures from Manama. Four protesters have since died in custody. The opposition says 40 people were killed.

Auditors also criticized the Defense Department for failing to document its efforts to verify the security and accountability procedures in countries receiving sensitive military equipment, while Pentagon staff in five of six Gulf countries did not document monitoring activities for less sensitive items.

"We need to ensure that the equipment is not being diverted to third parties, and that those groups and units who are the intended recipients are not implicated in human rights violations," said House Foreign Affairs Committee Chairwoman Ileana Ros-Lehtinen.

Gulf Cooperation Council countries -- Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates -- are among the US military's biggest clients, with some $22 billion in arms sales from 2005 to 2009.