Christians worldwide witnessed "unprecedented" levels of persecution in 2015 with more than 7,000 Christians killed for their faith, up from nearly 3,000 the year before, Open Doors USA disclosed on Wednesday as it released its annual World Watch List.

In a press statement, the watchdog organisation said approximately 2,400 churches were attacked or damaged, a figure that's double the number of churches attacked in 2014, according to Christian News.

"The levels of exclusion, discrimination and violence against Christians is unprecedented, spreading and intensifying," David Curry, president and CEO of Open Doors USA, said. "Christians, longing to stay in their home countries, are being forced to flee for their lives and for their children's lives."

For the 14th consecutive year, North Korea ranked as the most dangerous place to live as a Christian.

"Christianity is not only seen as 'opium for the people' as is normal for all communist states; it is also seen as deeply Western and despicable," Open Doors USA said. "Christians try to hide their faith as far as possible to avoid arrest and being sent to a labour camp. Thus, being Christian has to be a well-protected secret, even within families, and most parents refrain from introducing their children to the Christian faith in order to make sure that nothing slips their tongue when they are asked."

Open Doors USA estimates that between 50,000 to 70,000 Christians are imprisoned in labour camps in North Korea.

The second most dangerous place for Christians is Iraq, where Islamic violence continued to victimise the people, forcing Christians and other minority groups to flee their homes by the thousands to escape the brutal rule of the Islamic State (ISIS) jihadist and terrorist organisation.

The rest of the top 10 countries where Christians are persecuted the most, according to Charisma News and Religious News Service, are: (3) Eritrea; (4) Afghanistan; (5) Syria; (6) Pakistan; (7) Somalia; (8) Sudan; (9) Iran; and (10) Libya, which appeared on the list for the first time.

Aside from ISIS, two other radical Islamic groups continued to victimise Christians in 2015. These are the Boko Haram and al-Shabaab organisations based in Africa. These two terrorist groups are active in Somalia, Sudan, Libya and Nigeria, which ranked 12^th in the list.

"Less well known are the tens of thousands of Christians leaving the 12 sharia states of northern Nigeria, where 27 million Christians remain second-class citizens, and now many thousands are fleeing the anti-Christian violence of Hausa-Fulani herdsmen in the country's mid-section," Open Doors USA said.

"Official estimates seem to be the tip of the iceberg," it continued. "In Kenya, many Christians are fleeing from the Muslim-majority areas. Tens of thousands continue to brave desert and trafficking gangs to leave Eritrea, many ending up in Europe..."

Curry said the list should remind Christians to pray for their fellow believers in Christ worldwide and not forget their suffering.

"For Christians in the West, the Open Doors World Watch List serves as a clarion call to pray, advocate and remember their persecuted fellow Christians," he said.