An international conference aimed at raising aid for the victims of the Syrian conflict raised just over half of what the UN said was needed to support refugees from the country, as aid charities warn of “unmet and growing needs” among survivors.

The Brussels II summit, which was jointly organised by the European Union and United Nations and held on Tuesday and Wednesday of this week, raised $4.4bn (£3.2bn) – well short of the roughly $7-8bn the UN organisers had estimated was required.

Thanking the EU, Germany and Britain for making large contributions, Mark Lowcock, the UN’s humanitarian chief, said the money was “a good start” but that it would have to be saved for desperate cases given the shortfall.

“We are talking about a large sum of money and there is a lot of pressure on the financiers,” he told reporters, though he predicted that that contributions would grow further.

“The key issue is to make sure ... priority is given to those in most need and those most vulnerable.”

Aid organisations, many of whom have presences on the ground in the conflict, said the conference “did not go nearly far enough” to provide support.

“Though the crisis is now in its eighth year, the unmet and growing needs of millions of men, women and children mean that donor countries cannot show any sign of fatigue,” charities Care, IRC, Mercy Corps, NRC, Save the Children, Oxfam, Humanity and Inclusion, Action Against Hunger, and World Vision said in a joint statement.

“This conference did not go nearly far enough to provide adequate support to the millions of Syrians in need of assistance and who are left facing an uncertain future.”

Participants at the Brussels summit: donor countries cannot show any sign of fatigue, say charities (Getty)

The organisations also added that the donor countries at the conference “have once again done nothing to increase resettlement beyond the paltry 3 per cent of Syrian refugees they have taken in, favouring instead to leave them in Syria’s neighbouring countries”.

Lebanese prime minister Saad Hariri, who faces elections in two weeks and whose country has well over 2 million refugees despite being half the size of Wales (which has a population of around 3.1 million), said the plight of Syrians was simply getting worse.

“The bitter truth is that despite all our combined efforts, conditions have deteriorated. Lebanon continues to be a big refugee camp,” he said.

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Britain pledged an extra £250m in humanitarian aid for Syria over two years on Wednesday. The announcement takes its commitment up to £450m for Syria and the region in 2018, with £300m earmarked for 2019, bringing the total UK aid to the region to £2.71bn.

Alistair Burt, the UK’s Middle East minister said: “This is the world’s greatest protection crisis. If you look at what’s happened and what’s been done to people – breaches of humanitarian laws, the weakening of multilateral norms that we have seen for a long time – it’s all focusing on Syria,” he said.

Syria bombings: US, UK and French military air strikes wreckage Show all 13 1 /13 Syria bombings: US, UK and French military air strikes wreckage Syria bombings: US, UK and French military air strikes wreckage The wreckage of the Scientific Studies and Research Centre in the Barzeh district, north of Damascus, which was targeted by the US, UK and France air strikes. AFP/Getty Syria bombings: US, UK and French military air strikes wreckage A Syrian soldier films the damage of the Syrian Scientific Research Center surrounded by papers and rubble. AP Syria bombings: US, UK and French military air strikes wreckage Firefighrers extinguish smoke that rises from the damage. The Pentagon says none of the missiles filed by the U.S. and its allies was deflected by Syrian air defenses, rebutting claims by the Russian and Syrian governments. AP Syria bombings: US, UK and French military air strikes wreckage The wreckage of part of the Scientific Studies and Research Centre compound . AFP/Getty Syria bombings: US, UK and French military air strikes wreckage Part of a building collapsing, surrounded by the wreckage. AFP/Getty Syria bombings: US, UK and French military air strikes wreckage Further damaged to the Scientific Studies and Research Centre compound. AFP/Getty Syria bombings: US, UK and French military air strikes wreckage Lt. Gen. Kenneth McKenzie, the director of the Joint Staff at the Pentagon, also says there also is no indication that Russian air defense systems were employed early Saturday in Syria. AP Syria bombings: US, UK and French military air strikes wreckage A Syrian soldier sprays water on the wreckage. AFP/Getty Syria bombings: US, UK and French military air strikes wreckage Syrian state news agency SANA reported several missiles hit a research centre in Barzeh, north of Damascus, "destroying a building that included scientific labs and a training centre". AFP/Getty Syria bombings: US, UK and French military air strikes wreckage A Syrian soldier films the damage. AP Syria bombings: US, UK and French military air strikes wreckage Damage to the Scientific Research Center building that was hit by the strikes. EPA Syria bombings: US, UK and French military air strikes wreckage The Scientific Studies and Research Centre was one of the targeted buildings by the US, UK and France. AFP/Getty Syria bombings: US, UK and French military air strikes wreckage Further damage to the centre. EPA

Germany meanwhile pledged an additional billion euros (£870m). “In Syria alone there are still more than 13 million people who are dependent on humanitarian aid,” the country’s foreign minister Heiko Mass said. “We must not leave the people in Syria alone.”