Many Syrian refugees in Lebanon are not able to access crucial medical care, Amnesty International has warned.
In its new report, Agonising Choices: Syrian refugees in need of health care in Lebanon, the NGO said the situation is so desperate that in some cases refugees have resorted to returning to Syria to receive the treatment they need.
Audrey Gaughran, director of Global Thematic Issues at Amnesty International said: "Hospital treatment and more specialised care for Syrian refugees in Lebanon is woefully insufficient, with the situation exacerbated by a massive shortage of international funding.
"Syrian refugees in Lebanon are suffering as a direct result of the international community's shameful failure to fully fund the UN relief programme in Lebanon."
The health system in Lebanon is highly privatised and expensive, leaving many refugees reliant on care subsidised by the UN Refugee Agency, UNHCR.
However, due to a shortage of funds the UNHCR has been forced to introduce a restrictive set of eligibility criteria for people in need of hospital treatment.
As a consequence, Syrian refugees who are in need of crucial medical treatments are often untreated.
Many refugees living with cancer and other long-term illnesses are also unable to afford expensive treatments they require in Lebanon.
"Both the UN and refugees are facing agonising choices," said Gaughran.
"UNHCR and its partners are prioritising primary health care and treatment for life-threatening emergencies. Such prioritisation is vital, but humanitarian health professionals on the ground speaking to Amnesty International were clear that the current limitations on support for hospital care for refugees could be lessened if the relief funding improved."
According to a latest report by the UN, at least 2.7 million Syrian refugees have fled to Lebanon and the number is expected to rise.
The UN has appealed for $1.7 billion (£1bn) for Lebanon in 2014, as part of a $4.2 billion UN appeal for Syrian refugees. However, only 17% of the funds have so far been secured.
The Syrian civil war, which has pitted president Bashar al-Assad supporters against rebels, has so far lasted for over three years.
According to the Syrian Observatory for Human Rights, the death toll in the conflict, was over 130,000 and millions of civilians have fled their homes.
The UN said it stopped updating the death toll as it is no longer possible to ascertain the exact number of the victims.