Elias Bou Saab, Lebanon’s new minister of education, does not mince his words. “Without more support, the Lebanese education system may collapse. It is that serious,” he says.

The population of the small Middle Eastern country, home to just over 4 million citizens, has swollen by more than a quarter over the past three years. As Syria’s uprising has grown into a vicious civil war, more than a million people have fled across the border into Lebanon. This influx has driven the country’s public education system to the brink.

Because of agreements that predate the war, Syrians can enter Lebanese schools on the same terms as local residents. Lebanon also has relatively few state schools, with the country’s middle classes tending to prefer the private sector.

Before the Syrian crisis began in 2011, there were about 275,000 pupils in Lebanon’s entire public education system. By the start of this academic year, about 100,000 Syrians had been added to that. Classrooms designed for 20 children are holding double that number, with teachers desperately trying to keep control.

Yet this is just the tip of the iceberg: it is estimated that only one in four school-age Syrian refugees are currently enrolled.

Mr Bou Saab recently left his job as executive vice-president of the American University in Dubai to tackle one of the Middle East’s largest ever educational crises, and he accepts that the challenge is daunting. “There are 400,000 Syrian refugees between the ages of 2 and 18 that are eligible to be in school. That is more than the number of Lebanese [in the system],” he says.

With Lebanon’s economy static, the government has few funds to spare. As such, there is little chance that the country can continue to expand its services and get these children back into education. “If they are out of school for two or three years, it will be very difficult to get them back,” Mr Bou Saab adds. “This generation [of Syrians] may be lost if we don’t get real help.”

The country has sought out short-term strategies to alleviate the pressure. In September, it introduced a second-shift programme, which involves schools teaching Lebanese children in the morning and Syrian students in the afternoon. Although critics have warned that this approach could increase stigma against refugees, the scale of the crisis has made it necessary.

Among the leading international bodies working in Lebanon is the Norwegian Refugee Council (NRC), which provides various degrees of support to more than 25,000 students across the country. Olivia Kalis, spokesperson for the NRC, says the second-shift approach has enabled thousands of Syrians to access an accredited education. “This is an important achievement which we must recognise and encourage,” she says.

Yet, she adds, there are serious problems. Second-shift schools are often located far from areas where refugees are based. This means that children are forced into travelling long distances to get to school and often arrive home after nightfall.

Ultimately, however, organisational changes can only have so much impact on a situation of this scale. Just to provide children with the most basic education requires millions of dollars, especially in a relatively expensive country such as Lebanon. Ms Kalis points out that every child the NRC supports costs the charity an average of $1,200 (pound;700) per school year, with transport alone coming to $200.

More funding is desperately needed, but finding it is becoming harder as Syria’s plight slips down the global news agenda. In December, Lebanon, together with the United Nations, asked for $1.7 billion aid for refugees in the country for the whole of 2014. To date they have received about $280 million, roughly 17 per cent of the total, leaving the UNHCR refugee agency facing serious cuts in support.

Yet Mr Bou Saab is confident that he can turn the tide, at least in the education sector. Working with former British prime minister Gordon Brown, he has set out to raise $590 million to educate the 400,000 child refugees in Lebanon. Mr Brown, now UN special envoy for global education, is working on a “No Lost Generation” fund for Syrian refugees.

Mr Bou Saab, who recently travelled to Washington DC to drum up support, says he is confident of international backing. “Gordon Brown is fully supportive of this idea; he is giving it a lot of attention. He already raised some funds and he is continuing to do so,” he says. “We want to try to help him convince donors that this is an important matter and we cannot leave a whole generation behind.”

In a country where corruption is rife, Mr Bou Saab is refreshingly willing to accept that going directly through the government may not be palatable for international donors worried about keeping track of their taxpayers’ money.

Instead, he proposes that donations go through a trust fund run by the World Bank or other international bodies. “I don’t want the money to have to come to the government and the government to have to spend it, because that will be questionable and I don’t need this headache,” he smiles.

His priority, he stresses, is to ensure that the education system continues to function, not just for the refugees but also for the local population. “If we collapse, we collapse for the Lebanese and for the Syrian refugees. It will be a big disaster,” he says.