A drone strike in eastern Yemen has killed at least five people in the first such raid since the army launched an offensive against al-Qaeda-linked fighters last month.

The pilotless aircraft targeted a vehicle carrying "al-Qaeda members" near Al-Husun, a village in Marib province, one tribal source told the AFP news agency.

The United States is the only country operating drones over Yemen, but US officials rarely acknowledge the covert drone programme.

Yemen's army launched a major offensive on April 29 against strongholds of al-Qaeda in the Arabian Peninsula (AQAP) in three provinces in the south and east.

It says it has inflicted heavy losses on the fighters.

The offensive was preceded by a wave of US drone strikes that killed scores of suspected al-Qaeda suspects last month in southern and central regions.

AQAP has been linked to a number of failed plots against the US, and its leader Nasser al-Wuhayshi recently appeared in a rare video in which he vowed to attack Western "crusaders" wherever they are.

Al-Qaeda uses the term crusaders to refer to Western powers, especially those countries which have intervened militarily in Muslim countries, such as Britain, France and the US.

The fighters took advantage of a 2011 uprising that forced veteran strongman Ali Abdullah Saleh from power to seize large swathes of southern and eastern Yemen.

The army recaptured several major towns in 2012, but has struggled to reassert control in rural areas, despite the backing of militiamen recruited among local tribes.