Beirut - Islamic State fighters on Wednesday staged their most significant push yet into the Syrian capital Damascus while Syrian rebels took over the only functioning border outlet with Jordan, the head of the Britain-based Syrian Observatory for Human Rights told dpa.
Rebels led by the Al Nusra Front took over the Nassib crossing to Jordan, Abdel Rahman said. Jordan had earlier closed the crossing from the Jordanian side following heavy clashes between Syrian government troops and rebels near the outlet.
"The rebels managed to take the Syrian side of the Nassib crossing, while regime forces withdrew from the area," Abdel Rahman said.
The crossing mainly serves as a transit point for trucks transporting goods to Jordan and the Gulf market.
Refugee camp overrun
Throughout the day, a Palestinian refugee camp on the southern outskirts of Damascus was the scene of a chaotic struggle between Islamic State and another faction fighting in Syria.
Islamic State fighters overran the sprawling Yarmuk refugee camp, entering from the nearby district of Hajar al-Aswad and controlling most of the camp, Abdel-Rahman said.
They targeted the offices of the Palestinian faction Aknaf Beit al-Maqdis (Environs of Jerusalem) in the camp, according to witnesses.
Also read: Morocco: ISIS cell brought in arms through Spanish enclave
By late in the day, Aknaf Beit al-Maqdis managed to take back a few of the posts from Islamic State. The group is reportedly made up of members of Hamas, the Islamist group in control of the Palestinian Gaza Strip.
But it appeared that the Islamic State was still in control of most of the camp.
There was no official comment in Damascus.
Before the Syrian uprising that started in 2011 against the regime of Syrian president Bashar al-Assad, some 150 000 Palestinian refugees lived in the Yarmuk camp.
According to the UN refugee agency, some 18 000 Palestine are still living there.
The Nassib border crossing, located 14km south-east of Syria's Daraa province, was the last operational border crossing between Syria and Jordan which was still held by the regime forces.
Jordanian Interior Minister Hussien al-Majali said its country's closure of the Nassib crossing was a temporary precautionary measure aimed at protecting travellers' safety.
Islamic State, which is also active in neighbouring Iraq, has grabbed large parts of Syrian territory in recent months.
Hardline groups have recently featured prominently among the rebels fighting to oust al-Assad.
Meanwhile, the head of the al-Qaeda linked Al Nusra Front called in an audio message for Islamist groups fighting in Syria to unite and join forces "for the victory of Islam and Muslims."
Abu Mohammad al-Julani warned four days after Islamic rebels led by his group took control of Idlib city in northwestern Syria that "maintaining the control of the whole city is harder than seizing it".
Also read: ISIS releases Bangladeshi hostages in Libya oilfield attack
He vowed in his message that Idlib's residents would be treated well and that a council from various fanctions would be formed to serve the needs of the people.
Idlib, located near a highway linking the Syrian capital Damascus to the northern city of Aleppo, is the second provincial city captured by jihadists from regime troops.
In 2013, the Islamic State militia seized the north-eastern city of Raqqa from Syrian President al-Assad's troops and turned it into a de facto capital in the war-torn country. The Jihadist group has imposed strict Islamic rules on the people in Raqqa and have used abusive means to implement it.
'Liberation' from extremists
In Iraq, Prime Minister Haider al-Abadi arrived in the northern town of Tikrit on Wednesday, a day after he announced the "liberation" of the strategic town from the Islamic State extremists.
Al-Abadi toured the town, holding the national flag, and said that his government would work hard for the return of residents displaced by Islamic State's takeover of Tikrit around nine months ago.
The Iraqi Defence Ministry confirmed that Tikrit, the hometown of late dictator Saddam Hussein, had been "liberated".
"All terrorists who had tried to escape from the troops' advance were killed," the ministry said in a statement without giving casualty figures.
The ministry said the "victory" in Tikrit would mark a new start for wresting back other areas controlled by militants in northern and western Iraq.
Tikrit is strategically situated between Baghdad and the Islamic State-held city of Mosul.
Last week, Iraqi troops and allied Shiite militiamen, backed by US-led airstrikes, started the last phase of regaining Tirkit from the radical Sunni group.
Establishing full control over Tikrit should make it easier for Iraqi forces to regain Mosul, the country's second-largest city.
Islamic State forces captured Mosul and Tikrit last June after Iraqi government troops suffered a stunning collapse.