Intense fighting between Syrian government troops and insurgents in Syria's central Hama province displaced some 100,000 people over eight days between late August and early September, the UN humanitarian agency has said.
Earlier this month, insurgents pushed northward in Hama province, surprising government troops and dislodging them from areas they controlled around the provincial capital, also called Hama, including a military base and towns and villages near the highway to Damascus.
The offensive, led by an ultraconservative Islamic group, Jund al-Aqsa, and also involving several factions from the Western-backed Free Syrian Army, incurred an intense government bombing campaign that killed dozens of people.
The fighting and the aerial bombardment sent tens of thousands of people fleeing for safety, creating the latest wave of displacement, part of a pattern that has left nearly half of the Syrian population displaced since the war began in 2011.
In a "flash update " on Tuesday, the Office for the Co-ordination of Humanitarian Affairs (Ocha) said figures from a camp coordination group show nearly half of the displaced from Hama arrived in the neighbouring rebel-held Idlib governorate.
Others fled toward government-controlled Hama city, where four mosques were converted into temporary shelters, Ocha said. Dozens of schools in rural areas of Hama province were also turned into shelters.
A shortage of shelter space means many displaced families are sleeping outdoors in parks in Idlib, the UN agency said.
Most of those fleeing left towns and villages in government areas as the rebels advanced. They feared a violent government response to the insurgent offensive, according to Ahmad al-Ahmad, an activist from Hama.
"Wherever the regime is driven out of an area, it ends up destroying it," he said in a message to The Associated Press.
In at least one air strike last week, government warplanes struck a van carrying displaced people fleeing Suran, a town north of Hama city, activists said. The government says it is targeting "terrorists".
Ocha said the United Nations has sent an "inter-agency convoy with life-saving supplies to Hama" and was evaluating the humanitarian situation.
An estimated 11 million Syrians have fled their homes since the outbreak of the civil war, now in its sixth year. Of those, 4.8 million are refugees with nearly seven million displaced internally.
In London on Wednesday, Syrian opposition leaders unveiled a plan for a political transition designed to bring an end to the war. It called for the departure of President Bashar Assad after six months and for elections to be held after two years.
The High Negotiations Committee (HNC) envisaged a three-phase plan, beginning with six months of negotiations with Mr Assad's government to develop a signed agreement on the "basic principles" of the transition process.
This would be followed by the establishment of a transitional government body and the departure of Assad "and his clique," according to HNC chief Riad Hijab.
The HNC called for UN-supervised elections to be held 18 months thereafter. Mr Hijab conceded there were formidable obstacles hindering the implementation of this plan.