Follow the latest on the earthquake in Turkey
The UN was urged on Tuesday to open up new aid routes to Syria amid fears that radio silence from the country is a sign of a terrifying earthquake death toll.
Britain said it was working to open corridors via Turkey as the world's response to the earthquake collides with the politics of the region.
While images pour in of colossal damage on the Turkish side of the border, Mike Noyes, humanitarian director for the charity ActionAid, said a lack of information from Syria was especially alarming.
“There might not even be anyone on the ground to ask,” he told The National.
At least 5,000 people are believed dead in Turkey and Syria after the 7.8-magnitude earthquake and severe aftershocks.
Hundreds of the victims were in opposition-held northern Syria, which receives wartime aid via a single crossing point from Turkey.
A UN resolution allows it to enter without the approval of President Bashar Al Assad's government. But other crossing points from Iraq and Jordan have been closed amid wrangling with Russia, an ally of Mr Assad, on the UN Security Council.
A UN spokeswoman said on Tuesday that the flow of aid from Turkey had temporarily halted because of damage to roads in the earthquake.
“Some roads are broken, some are inaccessible. There are logistical issues that need to be worked through,” spokeswoman Madevi Sun-Suon said.
ActionAid, which is sending staff from the UK to Jordan to free up colleagues with local language skills, is asking for donations to help buy tents, food and warm clothing for people affected by the earthquake.
Mr Noyes expressed concern about women and girls being abused while in a shelter with unknown strangers, who might offer food and warmth that it would be “tempting to take”, based on evidence from previous disasters.
Another challenge is that local humanitarian staff have themselves been affected by the earthquake and even lost family members, but they still continue trying to help, he said.
“It’s a challenge to be overcome, not a reason to stop doing it,” he said.
Earthquake strikes Turkey and Syria — in pictures
The UK's Development Minister Andrew Mitchell said arranging aid for an “ungoverned space” in wartime Syria was “an additional problem at a desperate time”.
Speaking for the UK government on the morning media round, Mr Mitchell said the first 72 hours after the disaster were the most crucial as Britain co-ordinates with the UN.
“We hope that the UN will be able to negotiate additional crossing places,” he said.
“If you look at the geography, the way in is from Turkey. It's over that border which is very constricted, and that's an additional problem at a desperate time for people who've already suffered so much in northern Syria.”
Syria's UN envoy Bassam Sabbagh said the Assad government, which opposes cross-border aid, was ready to provide assistance to “all Syrians in all territory of Syria”.
“If anyone would like to help Syria, they can co-ordinate with the government and we will be ready to do so,” he said.
But concerns have been expressed about relying on the Syrian regime for aid, with Amnesty International saying help should be delivered regardless of the government's consent.
“With humanitarian help in an armed conflict it is especially important to bear in mind the risk of international aid being misused, and not to strengthen the Assad regime,” said German MP Lamya Kaddor.
Even before the tragedy, dilapidated buildings in Syria often collapsed.
The UN's refugee agency said some people affected by the earthquake were living in flimsy shelters, tents and partially destroyed buildings.
“After 12 years of civil war, large parts of infrastructure were destroyed in any case and there is no secure healthcare provision available,” said German charity Action Against Hunger.
A British charity called UK-Med is sending a team of six people on Tuesday, including surgeons, paramedics, medical and logistics staff to assess needs on the ground.
“Decisions on when to fully mobilise the charity’s resources have to be made in co-ordination with the Turkish authorities and WHO, chief executive David Wightwick told the BBC.
“The issue is do we then fully mobilise them, get them and all the equipment on the plane and get it where it’s most needed? It’s that decision, where it’s most needed, that takes up the first day or so.”
