Opposition activists said an estimated 10,000 refugees had been stranded at one crossing point for the past several days.

The latest spike in the number of people seeking to cross into Turkey appears to have been caused by the latest fighting in the border town of Azaz, which is reported to have been bombarded by a Syrian fighter jet early on Monday.

An official with Turkey's AFAD aid organization told the Reuters news agency that the country was continuing to let in Syrian refugees but that it was being more careful than before in processing them due to security concerns.

"We are trying to distribute aid to those on the other side of the border. On Saturday, their numbers were around 7,000 to 8,000," the unnamed official said.

Turkeysays it has already taken in more than 80,000 refugees since the Syrian conflict began almost a year and a half ago with demonstrators calling for political reforms.

Red Cross boss to visit

Meanwhile, the head of the International Committee of the Red Cross (ICRC) was to travel to Damascus on Monday for meetings with senior officials, including President Bashar Assad, to discuss the deteriorating humanitarian situation in the country.

"At a time when more and more civilians are being exposed to extreme violence, it is of the utmost importance that we and the Syrian Arab Red Crescent succeed in significantly scaling up our humanitarian response," Peter Maurer said in a statement prior to arriving in the Syrian capital.

He was expected to use his meetings to push for access for ICRC workers to the civilian population affected by the conflict as well as detainees.

pfd/mz (Reuters, dpa)