All staff at a hospital serving the besieged Syrian city of Aleppo have been given a month's notice after a British medical charity blamed red tape for its closure.

Half a million people in the war-torn country will lose access to desperately needed healthcare when Atareb hospital, operated by the British-based aid agency Hand in Hand for Syria (HIHS), closes within the next few days.

It would be a disaster for local people as well as for the medical staff, who included some of the last remaining doctors in Syria, and their families, said the charity's head of logistics, Fadi al-Dairi, speaking from the Syrian-Turkish border.

He said the charity has enough money from donors to keep the hospital running, but cannot get it into the country, because it needs a partner to channel the funding, and established charities are pulling out of Syria.

"It's because of bureaucracy, red tape," he added. "We have the expertise, but not the experience."

Al-Dairi said the charity was unable to apply for help from the UK's Department for International Development or a UN agency because it had not been running for three years. "We only set up to respond to the humanitarian crisis in Syria, so of course we are not yet three years old. We have been begging for help, but have had no firm commitment from any of the bigger aid agencies, whom we need to get the money we have to where it needs to be.

"Already all the aid agencies are only meeting 20% of the need within Syria. The loss of this hospital is a tragedy, especially when hospitals inside Syria are being bombed every day."

The EU reported in May that since the crisis began, 200,000 people have died in Syria because of the lack of healthcare, far more than the 164,000 thought to have been killed in fighting.

The hospital is just 20 miles from Aleppo, one of the hardest-hit areas of Syria. It provides free care to anyone, regardless of political or faith affiliation. The hospital became well-known to British audiences after a BBC Panorama programme, Saving Syria's Children, was screened last September, and showed the hospital treating casualties from an incendiary bomb attack on a school.

Omar Gabbar, an NHS consultant from Leicester who leads the British medical team for HIHS and has worked at Atareb, said the consequences of the hospital's closure would be dire: "About half of all Syrian hospitals have already been damaged or destroyed, and Aleppo only has 143 doctors remaining out of a pre-conflict 2,500. Around half a million people, over a huge area, will have no access to treatment for conflict injuries or ongoing normal medical conditions. Approximately 200,000 of these are internally displaced persons already facing a wide range of difficulties.

"One of the very few remaining kidney dialysis units left in northern Syria will shut. Essential reproductive health services will no longer be available. Three excellent operating theatres will remain empty, instantly ending the 265 lifesaving operations carried out there each month. 34,500 injured people a year will have no access to emergency care, and 26,000 outpatient clinic appointments will be lost. The laboratory will close, as will all the specialist departments including orthopaedics, ophthalmology, gynaecology, neurology, and many more. This leaves the hospital's 98 staff with no income, no longer able to support their family members. This is a massive blow."

Faddy Sahloul, co-founder and chairman of HIHS, said: "We set up Atareb hospital early in 2013 in an area we identified in great need. "The hospital's funding comes from a European donor fund which supports global emergency response, and reaches us via an NGO partner. This arrangement has been incredibly successful as it has enabled us to provide treatment to more than 92,000 Syrian people at Atareb over the last year. However although that funding is still in place, our one-year agreement with our NGO partner has come to an end.

"Despite our very best efforts, we have not yet been able to secure a replacement partner for Atareb hospital because of the complexities faced by NGOs trying to operate inside Syria, so we have now launched an appeal to secure emergency funds to keep the hospital open while we continue our search for a new partner. We welcome all enquiries from any individual or NGO interested in beginning discussions with us."

HIHS operates five other hospitals and supports more than 140 makeshift field hospitals, taking in a fleet of 32 ambulances and has opened a blood bank. It trains large numbers of medical staff in the treatment of conflict-related injuries.

Dr Rola Hallam, a British-Syrian NHS doctor and member of the HIHS medical team in the UK, said it was heartbreaking: "It took blood, sweat and tears, for a year, to get it up and running, and it was amazing to see it do such great work in such hard conditions. At a time when Syrian healthcare is in tatters, it feels like a crime not to keep its doors open."

A dedicated appeal page has been set up at www.justgiving.com/HIHS-Atareb-Hospital with the campaign hashtag #SaveAtarebHospital.