Hundreds of Sunni tribal fighters have already been fighting alongside Shiite militias, known as Popular Mobilisation Units, after receiving promises from the government in terms of weapons and salaries.

Majid Salim Ahmad, a former Iraqi army soldier, said that many of the tribal fighters and militia were experienced, having fought against al-Qaida.

But he also said ISIS were better armed and organised, and that the Sunni fighters were hoping for more weapons and support.

Brigadier Ahmad Abdullah Mattar, who was present during the graduation ceremony, said Anbar residents were determined to rid their land of ISIS extremists, which he said was clear from the numbers of volunteers signing up.

The Popular Mobilisation Forces were called to battle in Anbar after the fall of Ramadi.