An international aid official says 32 trucks have left for the Syrian-Jordanian border to deliver water to tens of thousands of Syrian refugees who have been cut off from aid since earlier in the week.

He says Thursday's shipment marks the first confirmed attempt to send water from Jordan to the stranded refugees since Jordan sealed the area in response to a deadly attack on its troops Tuesday.

He spoke on condition of anonymity because he was not authorized to brief reporters.

Refugees warned Wednesday that people had begun drinking dirty water.

For months, refugees stuck on the border received food and water from Jordan-based international aid agencies.

Government spokesman Mohammed Momani said that with the border sealed, aid groups will need to find alternatives to sending supplies from Jordan.