Beirut (AFP) - Syria's war has killed more than a quarter of a million people, uprooted over half the population and left much of the country in ruins since it erupted five years ago.

Here are some key facts and figures on the conflict:

- Huge death toll -

The fighting has left more than 270,000 people dead, according to the Syrian Observatory for Human Rights, a Britain-based monitor which relies on a large network of doctors and activist sources across the country.

Among those killed are around 80,000 civilians, including 13,500 children.

Far more people are feared dead, however, with an unknown number killed in detention at the hands of the government, rebels or jihadists.

UN investigators in February accused the regime of "extermination" in its jails and detention centres.

Handicap International, a French non-governmental organisation, said earlier this month that one million people had been wounded in the war.

And a Syrian aid group in January denounced the incessant bombing of medical facilities in the country, where it said 177 hospitals had been destroyed and nearly 700 health workers killed since 2011.

- Millions displaced -

In January, the United Nations said that 13.5 million people out of a pre-conflict population of 23 million had been forced from their homes.

The charity Save the Children said this month that at least 250,000 children are living under siege, with many forced to eat animal feed or leaves to survive.

An estimated 480,000 people are living under siege, according to the UN High Commissioner for Human Rights.

About 4.7 million Syrians have fled to neighbouring countries.

"It is the biggest population of refugees for a single conflict in a generation," Antonio Guterres, then chief of the UN refugee agency (UNHCR), said in 2015.

Most of the refugees are in neighbouring countries, notably Turkey, which has become the biggest host country with more than 2.7 million on its soil, according to UNHCR.

It is followed by Lebanon with over one million. More than two thirds of these live in "extreme poverty," according to the UN.

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Over 630,000 people have taken refuge in Jordan, according to UNHCR.

Around 225,000 Syrians have fled to Iraq and 137,000 to Egypt.

The refugees face poverty, health problems and growing tensions with local communities. Many live in makeshift camps and face significant restrictions on integration.

While the vast majority of refugees remain in the region, hundreds of thousands have tried to make the perilous journey to Europe, though not all reached its shores alive.

- Economy in ruins -

Experts say the conflict has set Syria's economy back by three decades, with almost all its revenues cut off and most of the infrastructure destroyed.

The economy has gone through a massive de-industrialisation as enterprises close, people go bankrupt, and looting and destruction take their toll.

The education and health systems are in ruins.

Exports have plunged by 90 percent since 2011, according to a senior official, while the country is also hit by severe international sanctions.

According to the oil minister, direct and indirect losses in the oil and gas sector amount to $58 billion (52 billion euros).

NGOs have said Syria is living almost without electricity, with 83 percent of lighting no longer working.