Islamic State jihadists penetrated the key Syrian town of Kobane on the Turkish border Monday and seized three districts in the city's east after fierce fighting with its Kurdish defenders.
Kobane, also known as Ain al-Arab, has become a strategic battleground between the IS group and its opponents, who include the United States and its Western and Arab allies.
The jihadists launched their latest assault on Kobane after a three-week siege with a wave of suicide bomb attacks, Mustefa Ebdi, a Kurdish activist from the town, said on his Facebook page.
The Syrian Observatory for Human Rights said the IS militants wrested three areas after day-long battles.
"They have taken the industrial zone, Maqtala al-Jadida and Kani Arabane in eastern Kobane after violent combat with Kurdish People's Protection Units (YPG) fighters" who had far fewer men and arms, it said.
The Observatory's Rami Abdel Rahman earlier said the jihadists and the Kurds were "clashing in the streets, between apartment buildings," sending hundreds of civilians into flight towards the Turkish border.
Kurdish fighters meanwhile ordered all civilians to evacuate Kobane, Mustafa Bali, a spokesman for Kurds in the city, told AFP, adding that some 2,000 people had left the city.
The IS advances came after an AFP photographer reported seeing two black IS flags flying on Kobane's eastern side, after the jihadists seized at the weekend part of Mishtenur Hill, although the US and its allies tried to slow them with air strikes.
In a sign of mounting desperation, a Kurdish female fighter blew herself up at an IS position east of Kobane on Sunday, the Observatory said.
It was the first reported instance of a female Kurdish fighter employing a tactic often used by the jihadists, said the Britain-based monitor, which relies on a network of sources inside war-ravaged Syria for its reports.
- Suicide bombers -
The bomber, in her 20s, was a full-time YPG fighter identified as Dilar Gencxemis, alias Arin Mirkan, from Kurdish-controlled Afrin in northwestern Syria.
"She killed dozens of gang members and demonstrated the YPG fighters' determined resistance," her group said.
On another front, twin IS suicide truck bombings killed at least 30 YPG fighters and security officers on Monday in the Kurdish town of Hasakeh, northeast Syria, the Observatory said.
Kobane has become crucial in the international fight against the jihadists, who sparked further outrage at the weekend with the release of a video showing the beheading of Briton Alan Henning.
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The video -- the latest in a series of on-camera beheadings 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.
They also revealed Kassig had sent them a letter in June.
"I am obviously pretty scared to die but the hardest part is not knowing, wondering, hoping and wondering if I should even hope at all," Kassig wrote.
- 'NATO to protect Turkey' -
IS began advancing on Kobane on September 16, seeking to cement its grip over a long stretch of the border. The offensive prompted a mass exodus, with some 186,000 people fleeing into Turkey.
The Turkish security forces used tear gas Monday to push dozens of reporters and Kurdish civilians away from the border zone, which has become increasingly dangerous because of stray mortar fire.
Parliament in Ankara last week authorised the government to join a US-led campaign against IS, but so far no plans for military action have been announced.
The new head of NATO said Monday it would protect member Turkey against any IS attack.
"Turkey is a NATO ally and our main responsibility is to protect the integrity, the borders of Turkey," said NATO chief Jens Stoltenberg.
British media, meanwhile, reported that Turkish hostages freed by IS last month may have been released as part of a prisoner exchange for up to 180 jihadist fighters.
The Times newspaper cited a list it had received saying that among them were three French nationals, two British, two Swedes, two Macedonians, one Swiss and one Belgian.
Extremist Sunni Muslim group IS has seized large parts of Syria and Iraq, where it has been accused of carrying out widespread atrocities, including mass executions, abductions, torture and forcing women into slavery.
After first launching strikes against IS in Iraq in August, Washington has built a coalition of allies to wage an air campaign against the group.
In Syria, the coalition carried out anti-IS strikes on Sunday and Monday near Raqa, Deir Ezzor and Kobane, where two jihadist "fighting positions" were destroyed, said US Central Command.
In Iraq, they also launched three raids, targeting the jihadists near Fallujah and Ramadi, it said, adding Belgium and Britain took part in the strikes.