Syrian civilians are fleeing the city of Aleppo in increasing numbers, the UN says, amid a lull in fighting between rebels and government forces.
The UN refugee agency says it has now registered almost 150,000 refugees in four neighbouring countries.
It said 6,000 had crossed into Turkey in the past week, many of them from the Aleppo area.
Earlier, the UK announced it was giving an extra £5m ($7.8m) in non-lethal equipment to the Free Syrian Army.
Foreign Secretary William Hague said the support would include more radio and satellite equipment, as well as portable power generators.
In another development on Friday, the US accused the Lebanese militant group Hezbollah of providing "training, advice and extensive logistical support" to the Syrian regime and added further sanctions against the group.
Hezbollah is designated as a terrorist organisation by the US and is already under heavy sanctions.
The US state department also imposed sanctions on Syria's state-run oil company, Sytrol, for conducting business with the Iranian energy sector.
Salah al-Din vow
Adrian Edwards, spokesman for the UN refugee agency (UNHCR), told reporters: "There certainly in the past week has been a sharp increase in the numbers arriving in Turkey, and many of the people are coming from Aleppo and surrounding villages.
"If you look at other areas, I think that the situation is more of a steady and continued increase, but where fighting happens we tend to see the consequences," he said.
The agency says there are now 50,227 refugees registered in Turkey; 45,869 in Jordan; 36,841 in Lebanon and 13,730 in Iraq.
"In several countries we know there to be substantial refugee numbers who have not yet registered," Mr Edwards said.
In Aleppo, rebels vowed to fight back after being largely ousted from the strategic south-west district of Salah al-Din on Thursday.
The Free Syrian Army withdrew after intense shelling by tanks and jet fighters.
William Hague: "Aid would include providing trauma and medical supplies, communications equipment and body armour"
"We will not let Salah al-Din go," FSA commander Abu Mohammed told AFP by telephone.
UK-based activist group, the Syrian Observatory for Human Rights, said government forces had also bombed Sakhur and Hananu in the east of the city.
Journalists from Reuters news agency reported seeing residents streaming out of Aleppo with cars packed with possessions, taking advantage of the calm spell.
AFP news agency reported that a bakery in the eastern Tariq al-Bab district had been hit by a shell, killing about 12 people and injuring at least 20.
State news agency Sana also reported that government forces had repelled a rebel attack on Aleppo's international airport.
The opposition Syrian National Council said part of Aleppo's 13th-century citadel had been damaged by shelling.
Activists also reported fighting in suburbs of the capital, Damascus.
Syrian President Bashar al-Assad is resisting international pressure to step down despite months of anti-government protests that have given way to civil war.
He has faced a string of high-status defections, including his former Prime Minister Riad Hijab, who fled to Jordan earlier this week.
US Secretary of State Hillary Clinton is due to arrive in Turkey later on Friday for talks over the weekend that are expected to be dominated by the Syrian crisis.