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.

Deadliest conflicts 2014
December 2, 2014: An Indian paramilitary trooper keeps guard near a polling station during the second phase of the state assembly election in Kulangham, north of SrinagarDanish Ismail/Reuters

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

Deadliest conflicts 2014
March 23, 2014: A man, killed after a boat carrying mostly Congolese refugees capsized, is seen inside a boat at the shores of Lake Albert during rescue operations by the Uganda Marine Unit in Ntoroko south-west of Uganda's capital KampalaEdward Echwalu/Reuters

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.

Deadliest conflicts 2014
June 6, 2014: A boy stands near a destroyed armoured vehicle on a road in the north-western province of OmranMohamed al-Sayaghi/Reuters

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

Deadliest conflicts 2014
July 24, 2014: Palestinians walk past a fire following what witnesses said was an Israeli air strike on a building in Gaza CitySuhaib Salem/Reuters

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.

Deadliest conflicts 2014
August 23, 2014: A building that witnesses say was hit by a rocket burns after clashes between rival militias in the Sarraj district in TripoliReuters

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

Deadliest conflicts 2014
March 9, 2014: A girl sits at the back of a truck as she prepares to flee sectarian violence with other Muslim families in a convoy escorted by African Union peacekeepers towards the border with Cameroon, in the town of Bouar, west of the Central African RepublicSiegfried Modola/Reuters

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.

Deadliest conflicts 2014
May 24, 2014: Somali government soldiers ride in their truck as they take up positions outside the Parliament building during a clash with Al-Shabaab militants in the capital MogadishuFeisal Omar/Reuters

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.

Deadliest conflicts 2014
September 14, 2014: A pro-Russian rebel displays a captured Ukrainian flag at the destroyed airport in Luhansk, eastern UkraineMarko Djurica/Reuters

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.

Deadliest conflicts 2014
March 24, 2014: A woman stands at the site of a house that was burned down during an attack by rebels in Mellit town in North DarfurMohamed Nureldin Abdallah/Reuters

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.

Deadliest conflicts 2014
December 16, 2014: Women mourn their relative Mohammed Ali Khan, 15, a student who was killed during an attack by Taliban gunmen on the Army Public School, at his house in PeshawarZohra Bensemra/Reuters

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.

Deadliest conflicts 2014
February 13, 2014: Rebel fighters hold up their rifles as they walk in front of a bushfire in a rebel controlled territory in Upper Nile StateGoran Tomasevic/Reuters

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.

Deadliest conflicts 2014
November 29, 2014: Security and emergency agency staff walk pass blood-stained walls at the Kano Central Mosque in Kano, after gunmen set off three bombs and opened fire on worshippers at the main mosque in north Nigeria's biggest cityReuters

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

Deadliest conflicts 2014
February 24, 2014: An Afghan National Army soldier is seen through damaged glass as he keeps watch at the Forward Base in Nari district near the army outpost in Kunar provinceOmar Sobhani/Reuters

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

Deadliest conflicts 2014
April 25, 2014: An explosion is seen during a car bomb attack at a Shi'ite political organisation's rally in BaghdadThaier al-Sudani/Reuters

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

Deadliest conflicts 2014
October 18, 2014: Smoke rises over the Syrian town of Kobani after an air strike, as seen from the Mursitpinar border crossing on the Turkish-Syrian borderKai Pfaffenbach/Reuters

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.