An armed group has kidnapped two foreigners working with Doctors Without Borders (MSF) in Yemen's east, a government source said Sunday, as the charity confirmed it had "lost contact" with some staff.

Over the years a number of foreigners have been abducted in Yemen by the country's heavily armed tribes and there have also been some kidnappings by jihadists. Iran-backed Huthi rebels, fighting a seven-year war with the government, have also detained several Westerners but most were later released.

"An armed group kidnapped two MSF workers, one a German national and the other Mexican, in Hadramawt," a Yemeni interior ministry source told AFP, adding that a "military campaign" was underway to track down the kidnappers.

Hadramawt is a large Yemeni province under the control of the internationally recognised government.

MSF on Sunday confirmed that it had "lost contact with some of our staff in Yemen".

"Out of concern for the safety of our colleagues we cannot share more details at this point," the medical aid group told AFP.

Last month, the United Nations said five of its staff members were abducted in the southern province of Abyan while returning to the port city of Aden "after having completed a field mission".

Al-Qaeda's Yemen branch -- Al-Qaeda in the Arabian Peninsula (AQAP) -- and militants loyal to the Islamic State group, have thrived in the chaos of Yemen's civil war.

The conflict began in 2014 after Huthi rebels seized the capital Sanaa and continued advancing. A Saudi-led military coalition intervened to prop up the government the following year.

The UN has estimated the war killed 377,000 people by the end of 2021, both directly and indirectly through hunger and disease while millions have been displaced, in what it calls the world's worst humanitarian crisis.