Yemeni forces, supported by U.S. military advisers and unmanned aerial vehicles, are battling al-Qaida elements in southern Abyan province.
Violence tied to al-Qaida in the Arabian Peninsula, the Yemeni arm of al-Qaida, has escalated since a yearlong political crisis led to longtime President Ali Abdullah Saleh resigning in February.
The ICRC said the assault on Abyan has led to a severe deterioration of the humanitarian situation there, making it difficult for volunteers for deliver assistance to those in need.
"Our staff were there a few days ago to assess the situation and found serious, urgent needs that, if not met, could lead to the displacement of over 100,000 people," Eric Marclay, the head of the ICRC delegation in Yemen, said in a statement. "Thousands of people have already fled to safer places."
Terrorism experts in London told al-Jazeera this week that Yemeni forces were battling al-Qaida elements largely integrated into the local population in Abyan.
The ICRC issued an appeal to all parties to the conflict calling for access to the area. As of Tuesday, it said, road access to the province was blocked.