European allies must pay far more towards humanitarian help for the victims of the Syrian civil war, MPs said as they warned the UK's disproportionate contribution was unsustainable without poverty-stricken parts of the world losing out.
France, Spain and Italy were singled out by the Commons international development committee as among those who had "manifestly failed to pull their weight" while Britain has already committed £600 million to the crisis, the second biggest contribution after the US.
The United Nations estimates that 10.8 million people are now in need of help as a result of the three years of brutal conflict in the region - with around 2.5 million Syrians registered as refugees in neighbouring Lebanon, Jordan, Turkey, Iraq and Egypt.
But a lacklustre international response to a global appeal for funds has left the UN and aid agencies struggling to deal with the scale of the crisis.
"The UK should do everything in its power to encourage other countries to increase their contributions," the report said.
The MPs noted that the UK had been able to make a growing input to the effort because the overall aid budget had been rising to meet the Government's commitment to meet the United Nation's target for 0.7% of a country's GDP to be devoted to foreign aid.
But success in hitting that level meant it could only be sustained at the expense of regular development work in poverty-stricken parts of the world, the report warned - calling for more clarity on the share of the budget given over to humanitarian emergencies.
The committee was particularly critical of the failure by the Department for International Development (DfID) to disclose the size of the contingency fund it reserves for dealing with crisis situations.
Among a number of specific recommendations about the Syria aid effort was a call for more money to be diverted to education, including paying for two "shifts" of classes at schools in Jordan and Lebanon.
At least half a million young refugees in neighbouring countries are out of school - and another 2.5 million in Syria itself - and the committee said having almost and entire generation uneducated spelled future disaster for Syria and the region.
Money should also be shifted away from those in vast refugee camps towards the 85% of refugees who were now living in communities in neighbouring countries, the MPs said.
While it was easier to get help to the camps, there was a huge risk that tensions with local populations would be inflamed unless there was action to tackle the pressure on existing services.
While the countries involved were not sufficiently poor to usually benefit from UK development help, the circumstances meant that programmes should be set up to ease the burden of the influx of refugees.
Jordan should also be encouraged to remove a block on refugees working as the extra tax would outweigh the natural reluctance, the MPs said.
Committee chair Sir Malcolm Bruce said the committee also backed the principle of concentrating efforts on helping people remain in the region and return home.
The UK has been criticised by campaigners for taking only small numbers of Syrian refugees - 50 have arrived so far under a limited scheme to provide a safe haven for the most vulnerable.
But the committee endorsed that approach and said it should continue to operate in a "constructive and compassionate" way.
"We argue that the overwhelming emphasis of UK funded humanitarian relief should be to help refugees remain in their own region, so that they have the potential to return home when this becomes possible," Sir Malcolm said.
A Department for International Development spokesman said: "We welcome this very positive report... which recognises that the UK has led from the front on the Syria crisis in helping more than a million men, women and children caught up in the conflict.
"Britain's leadership has leveraged multi-million pound commitments from others, but International Development Secretary Justine Greening has been clear that all countries must make good on their promises. We will continue to push the international community to live up to its responsibilities.
"The UK is recognised globally for its expertise in responding to humanitarian crises, alongside driving forward world-class long term development programmes in the world's poorest countries.
"To that end, UK funding is already supporting infrastructure and education programmes in Jordan and Lebanon."
A spokesman for Oxfam said: "The UK Government has played a crucial role in putting its money where its mouth is when responding to the humanitarian crisis in Syria and supporting refugees in neighbouring countries.
"Other countries need to be equally generous and many European nations are failing to meet their fair share of what is needed.
"Without Herculean efforts to find a political solution, this crisis is not going to end soon and governments need not only to increase their funding of the short term aid effort but maintain funding in the long term."