The UN says up to 3000 Syrian refugees are arriving in Jordan every day and at least 50,000 are waiting to cross the border.
Jordan has already warned it will close the border with Syria thatif there is a mass influx of refugees.
The UN refugee council said on Wednesday that more than 26,500 Syrian refugees have crossed into Jordan since 1 January, with more than 10,500 new arrivals in the past five days alone.
The BBC says that compares with 16,413 arriving in December; 13,000 in November and 10,000 in October.
The conflict in Syria began almost two years ago with demonstrations against the government of President Bashar al-Assad.
The UNHCR says there are now more than 670,000 registered refugees and more are awaiting registration in Jordan, Turkey, Lebanon, Iraq and Egypt.