Updated

Yazidi fighters protecting hundreds of families trapped on Iraq’s Mount Sinjar are pleading for help over fears that a “large scale attack” by the Islamic State is imminent.

After weeks of resistance, tribal defenders of the Yazidi religious minority were besieged by Islamic State jihadists on the mountain on Monday.

"The situation is really bad and it's worsening by the minute," Barakat, a fighter on the mountain told Reuters. "We are surrounded by IS militants from all four directions. The streets at the foot of the mountain are completely under IS control."

The fighter said 500-600 families are stranded on the mountain and helicopters that have been dropping supplies can only evacuate small numbers of people at a time.

Awar, another Yazidi fighter, said Thursday that ISIS militants are amassing on the eastern side of the mountain, according to Reuters.

"There's a strong possibility that a large scale attack is coming tonight or tomorrow morning," he added.

Yazidi fighters – who are short on supplies, like food and clothing – are pleading for more assistance, as their weapons are proving to be ineffective against Humvees operated by ISIS militants.

"The fighters are holding the ground and are putting a stop to any attempt at climbing the mountain," a third fighter, who asked to remain unnamed, told Reuters.. "We will stay here and fight IS in order to protect our land and our holy shrines."

Fighter Khalef Mamu told AFP that 1,200 fighters helped to defend the mountain and a commander of forces for the Yazidi religious minority was killed during an attack on Wednesday night.

“The humanitarian situation became very difficult because there is little food,” said Mamu.

Commander Dawud Jundi told AFP that 300 Islamic fighters seized nearby villages and then turned their focus to Mount Sinjar.

That renewed attack began at dawn on Monday when Islamic fighters attacked the southern part of the Mount Sinjar using Humvees and armored vehicles. Yazidi civilians were forced to retreat up the mountain where they are now trapped.

Earlier this year, thousands of mainly Yazidi civilians were trapped by Islamic State fighters, prompting the U.S. to pursue an airstrike campaign against the militant group.

ISIS has killed hundreds of Yazidis and has forced tens of thousands of others to flee for their lives since sweeping across Iraq, according to The Associated Press.