The world's 15 deadliest conflicts including Syria, Iraq and Afghanistan [Photo report]

The death toll in the world's most brutal conflicts in 2014 was more than 28% higher than the previous year, with bloodshed in Syria worse than all others for the second year running, according to a study released by the Project for the Study of the 21st Century think tank.

Data from sources including the United States military, the United Nations, the Syria Observatory for Human Rights and Iraq Body Count showed more than 76,000 people were killed in Syria last year, up from 73,447 in 2013.

Many of the most violent wars involved radical Islamist groups. Around 21,000 lives were lost in Iraq as the government fought with Islamic State (Isis), followed by Afghanistan with 14,638 and Nigeria on 11,529, according to the analysis that the think tank said could easily underestimate the actual figures.

15: Conflict in India claimed 976 lives in 2014, up from 885 in 2013.

14: Conflict in the Democratic Republic of Congo claimed 1,235 lives, down from 1,976 in 2013.

13: Fighting in Yemen claimed 1,500 lives in 2014, up from 600 in 2013. The advance of the Iranian-backed Houthis into the capital in September and to other regions, mainly in central and eastern Yemen, has been met with resistance from armed Sunni tribes, some of whom are backed by al-Qaeda militants.

12: The Israel-Palestinian conflict claimed 2,365 lives in 2014, a massive increase in the region following 2013.

11: Fighting between rival groups in Libya claimed 2,825 people in 2014, up from 643 in 2013. Islamist militants who have allied themselves to IS that controls parts of Iraq and Syria have recently spread their reach in the divided country, posing a challenge to the Tripoli-based government and its allied factions which have engaged them in battle.

10: Fighting in Central African Republic claimed 3,347 lives in 2014, up from 2,364 in 2013.

9: The conflict in Somalia killed 4,447, up from 3,153 in 2013. Al-Shabaab often targets official buildings and politicians in the capital Mogadishu in its efforts to topple the Western-backed government and impose its strict interpretation of Islam.

8: Fighting in Ukraine took the lives of 4,707 people in 2014, a dramatic increase for a country at peace in 2013. Its death toll exceeded conflicts in Somalia, Libya and Central African Republic.

7: Fighting in Sudan killed 5,335 people last year. Sudan and South Sudan still remain among the world's deadliest wars. If the countries had remained unified, the combined death toll would be higher than Afghanistan in the number three spot.

6: The conflict between Pakistan and the Pakistani Taliban killed 5,496 people. The Pakistani Taliban are allied with the Afghan militants of the same name and share a similar jihadist ideology. But they operate as a separate entity, focused on toppling the Pakistani state and establishing strict Islamic rule in the nuclear-armed nation.

5: Fighting between rebels and government forces in South Sudan killed 6,389 people in 2014. Both sides have been accused of ethnic-based atrocities, mass rapes and using child soldiers in the world's newest nation.

4: Nigeria was the fourth deadliest conflict with 11,529 people killed. The intensifying battle with Boko Haram resulted in almost three times those killed in 2013.

3: Approximately 14,638 were killed in Afghanistan, up from 10,172 in 2013.

2: Around 21,000 lives were lost in Iraq as the government fought with IS.

1: More than 76,000 people were killed in Syria in 2014, up from 73,447 in 2013.

At least 14 separate wars killed more than 1,000 people in 2014, up from 10 in 2013.

The research points to a developing trend. In 2014, the Australia and US-based Institute for Economics and Peace reported a rise in conflict-related violence every year since 2007.