Three of those held by the group in the eastern province of Diyala have reportedly been killed, according to a security official.

Abu Abdullah, a farmer, said a total of six gunmen barged into his home earlier this week and dragged away his 21-year-old son.

Mr Abdullah's son is just one of the 15 young men – all aged between 16 and 22 – who have reportedly been captured in the province for breeding birds.

Pigeon breeding is a popular hobby in the region, but it is said to be frowned upon by extremist Islamist fighters because they believe it is a distraction from worshipping Allah.

Mr Abdullah, 52, said he was standing beside his son when ISIS militants stormed the family home and kidnapped his son.

He told NBC News: 'I asked them why and they said: "He is not following the real Islam, he must be punished for being a pigeon breeder. This habit is taking him away from worshiping Allah."

'I begged them again to know where are they taking him, what are they going to do to him. They said he is going to be taken to be judged according to the Islamic Sharia.

'They pushed me, and when my son tried to stop them from pushing me they beat him. Then they put him inside the car and left.'

(dailymail.co.uk)