Fierce clashes have erupted between military forces and suspected al-Qaida-linked militants in southern Yemen, leaving at least 30 people dead.

Yemeni officials say the fighting broke out early Saturday when militants attacked an army post in the town of Mallah, in Lahij province. The area is near Abyan province, an al-Qaida stronghold.

Yemeni officials say at least 17 soldiers were killed in the unrest.

The Ansar al-Sharia militant group has claimed responsibility for the attack. Earlier this month, the group claimed responsibility for the death of an American teacher in southern city of Taiz.

In another development Saturday, relief organizations launched a massive vaccination campaign to combat a measles outbreak that has infected more than 4,000 people.

The U.N. says measles has killed more than 170 children since the outbreak began last year.

Geert Cappelaere, the UNICEF representative in Yemen, tells VOA that children are especially vulnerable.

“In a country like Yemen, an outbreak of measles is an incredible threat to the lives and survival of children not only because of the lack of immunization but also because of the incredible high levels of malnutrition.”

Cappelaere, who commented from Sana'a, said unrest from anti-government protests over the past year also contributed to the measles surge because it led to a decrease in the availability of social services.

“We saw in 2011, in certain parts of the country, a drop by 40 to 60 percent even of the number of children immunized.”

UNICEF and the World Health Organization are taking part in the second phase of an immunization program targeting eight million Yemeni children.