Jihadists are on the verge of seizing the key Syrian border town of Kobane, Turkey warned on Tuesday after a three-week assault by the Islamic State group that has left hundreds reported dead.
The fall of Kobane to IS would mark a major victory for the jihadists, who are fighting for a long stretch of the border with Turkey for their self-proclaimed "Islamic caliphate".
At least 412 people, more than half of them jihadists, have been killed in and around Kobane since mid-September, according to the Syrian Observatory for Human Rights, a Britain-based monitoring group.
Turkish President Recep Tayyip Erdogan warned that the strategically important town was "about to fall", saying a ground operation was needed to defeat the militants.
"The terror will not be over... unless we cooperate for a ground operation," Erdogan said in a televised speech.
With the fight for Kobane entering a crucial phase, Kurdish militia backed by US-led air strikes waged fierce street battles with the advancing jihadists, who pierced the town's defences on Monday.
Gunfire, explosions and the roar of fighter jets were heard from the Turkish side of the border, while a Kurdish flag was seen flying in the centre of Kobane, according to an AFP journalist.
The IS jihadists "are trying hard to capture the city", said Idris Nahsen, a Kurdish official still in Kobane, also known as Ain al-Arab.
"We need help from the international community," Nahsen told AFP by telephone. "Either we finish them (IS) or they will finish us."
Kurdish fighters have ordered civilians to evacuate the town, after the jihadists planted their black flags on its eastern side and entered Kobane on Monday.
The United States and its allies have launched nearly 2,000 air raids against jihadists in both Iraq and Syria in an attempt to stop their advance, including four strikes in Kobane on Tuesday.
In Iraq, at least 17 people were reported killed when a suicide bomber attacked an observation post used by Shiite militiamen watching for IS fighters crossing the Tigris River late Monday.
'Fight to last person'
In Syria, the Kurdish fighters are optimistic that their local knowledge of Kobane will compensate for their light weapons, said activist Mustafa Ebdi.
"They are fighting to defend their town and they say they will fight to the last person," he said.
Ebdi said the latest US air raids had little effect.
"The strikes hit the Mishtenur area," he said, referring to a plateau south of Kobane.
"But they (IS) aren't gathered there. There are other places they should be hitting," he said.
The battle has prompted some 186,000 residents to flee across the Turkish border.An official in the Turkish town of Suruc said on Tuesday that 700 people, including 47 wounded, had crossed the border from Syria overnight, both civilians and Kurdish fighters.
Seven bodies were also carried across the frontier.
Turkey last week won parliamentary approval for military intervention against IS in Syria and Iraq, but it has yet to announce any firm plans for military action despite the advance of the jihadists to its doorstep.
The United States has been backed by Arab and European allies in its military campaign in Iraq and Syria.
The Netherlands said its F-16s carried out their first strikes on IS in Iraq on Tuesday, targeting armed vehicles shooting at peshmerga Kurdish fighters.
Plea for mercy
IS, an extremist Sunni Muslim organisation, has taken advantage of the chaos unleashed by Syria's several-sided civil war to capture large parts of the country, as well as in neighbouring Iraq.
IS has been accused of carrying out widespread atrocities, including mass executions, abductions, torture and forcing women into slavery.
In northwestern Syria, meanwhile, a rival extremist organisation to IS -- the Al-Qaeda-affiliated Al-Nusra Front -- abducted a priest and several Christians on Sunday night, the Franciscan mission said on Tuesday.
The jihadists had sparked fresh outrage at the weekend with the release of a video showing the beheading of British aid worker Alan Henning.
The video -- the latest in a series of on-camera murders of Western hostages -- also included a threat to another hostage, US aid worker Peter Kassig.
His parents have issued a video plea for their son's release, urging his captors to show mercy towards the 26-year-old former US soldier who has converted to Islam.
Read: Jihadists pound key Syrian town after slaying Briton