Jordan's army denied on Wednesday that the US military is helping the kingdom handle an influx of Syrian refugees and prepare for other scenarios, including Damascus losing control of its chemical weapons.

"News reports that the United States is helping Jordan deal with the Syrian refugees or face dangers related to chemical weapons are not true," a Jordan Armed Forces spokesman said in a statement carried by state-run Petra news agency.

"The Jordanian forces are capable of facing any kind of threats."

A senior US defence official said in Brussels on Wednesday that a 150-strong force of planners and specialists – led by a senior US officer – was looking at ways to prevent the increasingly bloody Syrian civil war from spilling across Jordan's borders.

They are based at an outpost north of the capital Amman and just 35 miles (55 kilometres) from the border, making it the closest US military presence to the Syrian conflict, said the official, who asked not to be named.

"The presence of friendly and brotherly forces in Jordan is to conduct annual and routine military exercise. This is not new and has nothing to do with any regional issues or developments," the Jordanian army spokesman said.

He did not comment on whether US troops are currently stationed in the kingdom. The last joint exercises between the US, Jordanian and 17 other militaries were held in May.

Jordan, which says it is hosting more than 200,000 Syrian refugees, shares Washington's fears that the conflict could destabilise an already volatile region.

In July, sources close to the Jordanian government said "daily meetings are being held to examine the possibility of dispatching Special Forces (to Syria) if and when the Syrian regime falls to secure its chemical and biological weapons."

A New York Times report said US and Jordanian officials had discussed setting up a humanitarian buffer zone on the Syrian side of the border patrolled by Jordanian forces with US support but are holding off on the idea for now.