Suicide bombers from the Islamic State group, also known as Isis, on Sunday killed 12 trainees of the Iraqi security forces at a base near Tikrit, AFP reported.

A number of Isis suicide attackers entered the Speicher military base when a police force was attending a training programme, a spokesman and a police officer told AFP.

The police force that became the target was from Nineveh, located on the eastern bank of the Tigris River.

Isis, also known by its local acronym of Daesh, had killed at least 1,700 soldiers at Camp Speicher, a former US base, in mid-2014. 

The Isis-led attack at the camp comes days after the Iraqi military declared victory over the Sunni Islamist extremist group in the city of Ramadi in December.

The Isis militants have since then launched several counter-attacks on the Iraqi forces in areas surrounding Ramadi. The Iraqi military said Isis militants carried out suicide attacks on the outskirts of Ramadi.

"The majority of these are outside downtown Ramadi to the north and east," Baghdad-based coalition spokesman Colonel Steve Warren told AP. He added that Iraqi government forces have successfully repelled every attack.

Brigadier General Ahmed al-Belawi confirmed casualties among Iraqi forces, but refrained from giving exact numbers.

With the backing of US-led coalition airstrikes, Iraq won its fight against the extremist group that took control of a few major cities in the Middle Eastern country.

The Iraqi forces recaptured Ramadi on 27 December, 2015, and regained power in Baiji, Iraq's major oil refinery that was seized by Isis in June 2014, in October. In November, it was again successful in taking back Sinjar from Daesh after fighting with the jihadist group for over 15 months.

At least 10 Isis leaders were also killed during US-led coalition airstrikes in parts of Iraq and Syria in the last few months.