The International Committee of the Red Cross (ICRC) says gunmen have abducted six of its workers and one Red Crescent volunteer in north-west Syria.
The aid agency has had no contact with the gunmen, an ICRC spokesman says.
Earlier, Syrian state media said gunmen opened fire on Red Cross staff travelling on the Sirmin-Saraqeb road in Idlib province.
The ICRC says it has been struggling to gain access across Syria to provide aid to injured and displaced people.
“I am able to confirm that six ICRC staff members and one Syrian Arab Red Crescent volunteer have been abducted near Idlib in north-western Syria,” ICRC spokesman Ewan Watson told Reuters.
“We are calling for their immediate and unconditional release of this team which was delivering humanitarian assistance to those most in need – and we do that on both sides of the frontlines,” he said.
He declined to reveal the identity, gender or nationality of the abducted workers.
Syrian state news agency, Sana, earlier quoted an unnamed official as saying the workers were abducted and taken to an unknown location after gunmen blocked their path and shot at their convoy.
Mr Watson was unable to confirm if shots were fired, but he said the team’s vehicles were also missing.
Another ICRC spokesman, Saleh Dabbakeh, told Associated Press the attack took place at 11:30 (08:30 GMT) on Sunday.
It is not yet clear who carried out the kidnapping, but Syrian state TV blamed it on what it called “armed terrorists” – a term it frequently uses to describe anti-government rebels.