Drug dealer "Marai al-Ramthan, his wife and six children were killed in a Jordanian air force strike" in the eastern countryside of the Sweida province, near the Syrian-Jordanian border, the UK-based Syrian Observatory for Human Rights said.

"Al-Ramthan is considered to be the most prominent drug trafficker in the region, and the number one smuggler of drugs, including captagon, into Jordan" from that area, said the Observatory, which relies on a wide network of sources inside Syria.

Jordan has not yet commented on the strike.

It comes on the heels of a May 1 meeting with several Arab foreign ministers in Amman, during which Damascus had agreed to "enhance cooperation" with neighbouring countries "affected by drug trafficking and smuggling across the Syrian border".

Damascus said it would cooperate with Jordan and Iraq to identify sources of drug production and smuggling on its borders with the two countries, according to a statement from Jordan's foreign ministry.

It would also seek to "take necessary steps to end smuggling operations", the statement said.

On Sunday, the Arab League welcomed Syria back into the bloc after a more than decade-long suspension, securing President Bashar al-Assad's return to the Arab fold after years of isolation.

An AFP investigation in November found that Syria has become a narco state, with the $10 billion captagon industry dwarfing all other exports and funding both Assad and many of his enemies.

The main destinations are oil-rich Gulf countries, but Jordan has also become a transit route for the captagon trade.

Jordan's army had said last year that drug trafficking from Syria into Jordan had become "organised", with smugglers stepping up operations and using sophisticated equipment including drones, warning of a shoot-to-kill policy.

In February 2022, Jordan's army said it had killed 30 smugglers since the start of the year and foiled attempts to smuggle into the kingdom from Syria 16 million Captagon pills -- surpassing the entire volume seized throughout the whole of 2021.

Jordan has previously launched strikes targeting drug smugglers in Syria, some dating back to 2014.