The escalation of violence in Syria and related clashes in Lebanon are hampering the work of the UN refugee agency as the number of those fleeing the conflict reaches record levels, the UNHCR said.
"The deteriorating security situation in Lebanon is hampering our work to help refugees fleeing Syria's conflict, though operations are continuing," UN High Commissioner for Refugees spokesman Adrian Edwards said.
"Clashes between rival neighbourhoods in Tripoli continue, affecting the pace of registration from our new centre in the city" in northern Lebanon, he said.
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Registration of refugees in Lebanon's Bekaa Valley, near the eastern border with Syria, was also affected by security concerns in the wake of kidnappings of Syrians in the area, the UNHCR added.
Current refugee numbers in Syria's neighbours total more than 200,000, according to official figures.
These include 51,000 in Lebanon, 15,900 in Iraq, 61,000 in Jordan and more than 74,000 in Turkey, which has told the UNHCR it is building seven new camps.
People fleeing fresh fighting in southern Syria, including in Daraa, where the uprising broke out in March last year, are pouring into Jordan, with a record 2,200 crossing the border on Thursday night, the UNHCR said.
In Amman, Information Minister Samih Maaytah confirmed the record number of refugees who arrived on Thursday night, giving a slightly higher figure, and said the flow was putting pressure on the country.
"A record 2,324 Syrian refugees crossed into Jordan on Thursday night," said Maaytah, who is also government spokesman.
"There is a growing number of Syrian refugees entering Jordan daily, and that increases pressure on the kingdom, which hosts around 200,000 Syrians, in various fields," he added.
Maaytah also called on "the international community to increase its assistance to Jordan, to ease burdens resulting from hosting the Syrian refugees."
The UNHCR said, meanwhile, that staff inside Syria were having difficulty moving about because of the conflict, with forces loyal to President Bashar al-Assad pounding population centres across the country as they fought to suppress a rebellion which has killed around 24,500 people, according to estimates.
