A million people have been wounded in Syria's civil war and the country is suffering from a lack of regular supplies of medicine, according to a new report from the World Health Organisation.

Vaccination rates in the country have fallen from around 90% before the war to around 50%, while a series of diseases including typhoid and hepatitis have proliferated.

More than 200,000 people have been killed in the conflict, which erupted in 2011 after a popular uprising against the Syrian government was brutally put down by President Bashar al-Assad's security forces.

Around half of the country's population are displaced, with more than three million registered as refugees in neighbouring countries.

The country's health system has collapsed as the majority of public hospitals are not in use.

"In Syria, they have a million people injured as a direct result of the war. You can see it in the country when you travel around. You see a lot of amputees. This is the biggest problem," said WHO's Elizabeth Hoff, as cited by Reuters.

NGO's have reported that the Syrian government continues to block the passage of medical materials to areas held by rebels.

"What has been a problem is the regularity of supply. The approvals are sporadic," Hoff told Reuters.

With the conflict heading into its fifth year, the United Nations has launched a new humanitarian appeal for $8.4bn to assist more than 12 million displaced Syrians.

"Conflict has devastated millions of Syrians' lives, trapping them in conflict areas and denying them access to basic provisions and healthcare. Many live in fear, children can't go to school and parents can't go out to work," said the UN's Valerie Amos.

"This plan, if fully funded, can help us provide food and medicine for children, shelter families from the cold, and support those who are desperate and traumatized. Syria is a very difficult and dangerous place to work but the humanitarian community remains committed to helping the most vulnerable people caught in this crisis."