Syrian rebels have taken control over a key government checkpoint near a border crossing with Jordan after a longstanding battle with the army.

Rebels told Al Jazeera that the seizure of the Umm al-Mayathen checkpoint in Deraa province was significant in their bid to seize the Nasib border crossing.

"The Assad regime were using this checkpoint as a first defence line for the Nasib border crossing, and we fought with heavy weapons. We managed to take control of it," a rebel said.

While the Islamic State of Iraq and the Levant (ISIL) group is fighting in the north and east of Syria to carve out a "caliphate" run by Islamic law, Deraa province in the south has become a stronghold of moderate rebels fighting the regime.

Taking over the Nasib crossing would give rebels control over the entire border between Syria and Jordan.

Al Jazeera's Nisreen El--Shamayleh, reporting from Jordan, said that government forces have been shelling the area near the border heavily to stop the rebels from advancing and take control of the crossing.

"I would be very surprised if the rebels capture the Nasib crossing because the government still controls a lot of territory in Deraa," she said.

"The fighting is ongoing and it does not look like there is a clear winner yet."

Our correspondent added that there were reports of heavy casualties as government forces had shelled rebels in the area.

Fierce fighting was also raging between rebels and government forces in rebel-held districts on the outskirts of the capital Damascus on Thursday. 

The government said it had advanced in southeast areas of the province, but rebels denied the reports.

More than 190,000 have been killed since the war in Syria began in 2011.

Source: Al Jazeera