LONDON (Thomson Reuters Foundation) - The number of attacks on aid workers soared last year to the highest level on record, with Afghanistan the most dangerous country to be a humanitarian, a report on Tuesday said.

In all, 155 aid workers were killed, 171 wounded and 134 kidnapped in 2013 – a rise of 66 percent compared with 2012, according to the Humanitarian Outcomes report, published on World Humanitarian Day.

It said three quarters of the attacks took place in Afghanistan, Syria, South Sudan, Pakistan and Sudan amid worsening violence. There were 81 attacks in Afghanistan alone.

The death toll for 2014 shows little sign of abating. Already, 79 humanitarians have been killed this year, including several in Gaza, according to provisional figures.

"One aid worker killed in the line of duty is one too many," Valerie Amos, the U.N. emergency relief coordinator, said in a statement ahead of a memorial service for aid workers to be held in London's Westminster Abbey on Tuesday.

"Nurses, engineers, logisticians and drivers ... all take great risk doing their work in sometimes extremely dangerous and difficult circumstances," she added.

The U.N. General Assembly in 2008 declared Aug. 19 World Humanitarian Day to mark the day in 2003 when 22 people who were killed in a bomb attack on U.N. offices in Baghdad.


NEW WARFARE

The main reason for the increased attacks on aid workers is the changing nature of warfare, according to the U.N. Office for the Coordination of Humanitarian Affairs (OCHA).

Most wars used to be fought between national armies. But the majority are now waged within countries, and involve rebel groups who often target civilians on a massive scale.

"More and more we're seeing parties to conflicts around the world ignore the rules of war to achieve a political end –directly targeting civilians, carrying out collective punishment, inciting ethnic violence, impeding the delivery of lifesaving humanitarian supplies to affected people and attacking humanitarian actors themselves," John Ging, OCHA's director of operations, told Thomson Reuters Foundation.

"This has a huge impact not only on the security of humanitarian workers, but on the millions of people around the world who depend on the timely delivery of humanitarian assistance for their survival," he added.


NEARER THE FRONTLINE

Globally, the majority of attacks have been on the road. Some aid workers are attacked for helping people the combatants feel should not be helped, some are victims of robbery.

The increased militarization of aid has also put aid workers at risk, many experts say. In Afghanistan, U.S.-led NATO troops have distributed aid as a means of winning hearts and minds.

Aid agencies say this means many of those fighting the NATO forces view all aid agencies as legitimate targets.

Aid agencies are also taking greater risks, getting closer to the frontlines, an expert at the London-based thinktank Overseas Development Institute (ODI), said.

In the past, most aid was distributed in refugee camps across the border from the scene of the conflict.

"Today, there is an urge to be present in a conflict even when it's clearly unsafe for people to do so," Sara Pantuliano, director of ODI's Humanitarian Policy Group, told the Thomson Reuters Foundation.


(Reporting by Alex Whiting, Editing by Katie Nguyen.)