Battles have continued to rage on along Turkey's border between the Islamic State in Syria and the Levant (ISIL) fighters and Syrian Kurds as anti-ISIL coalition's military chiefs prepare to meet in the US capital.

Activists said the self-declared jihadist fighters fought their way on Monday into central Kobane in heavy clashes with the Syrian border town's Kurdish defenders, a day before a Washington DC meeting of the US-led coalition against the ISIL.

The offensive resulted in the ISIL claiming half of Kobane, despite more than three weeks of US-led air strikes in Syria aimed at stopping them and nearly a month after the fighters began their assault on the town.

US and Saudi fighter jets targeted seven sites around Kobane, the US military said on Monday, including ISIL staging posts used to try to cut Kobane from the outside world.

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Fighting has spread of late to less than a kilometre from the barbed wire frontier fence, with ISIL fighters carrying out three suicide car-bomb attacks in the border zone, according to the Syrian Observatory for Human Rights, which monitors the developments in Syria through sources on the ground.

The Britain-based group also said ISIL seized a major building in the city centre and squeezed the town's Kurdish defenders into its northern half bordering Turkey.

John Kerry, the US secretary of state, said on Sunday in Cairo that the US was deeply concerned about the "tragedy" in Kobane, but added that Kobane did not define the strategy for the coalition.

That failure in Kobane will be among the main points up for discussion at Tuesday's meeting in Washington DC of military chiefs from the 21 countries in the US-led coalition, as will Turkey's call for the establishment of a protective buffer zone. 

Australia, Bahrain, Belgium, Britain, Canada, Denmark, Egypt, France, Germany, Iraq, Italy, Jordan, Kuwait, Lebanon, the Netherlands, New Zealand, Qatar, Saudi Arabia, Spain, Turkey, the United Arab Emirates and the US will be represented at the meeting.

Turkey denies deal

Against this backdrop of continued tensions, Turkey has rejected reports that it and the US had come to an agreement for the coalition to use Turkish bases in the fight against ISIL.

"We are holding intense negotiations with our allies. But there are not any new developments about Incirlik," Bulent Arinc, Turkish deputy prime minister, said after a cabinet meeting in Ankara on Monday.

The Obama administration has been pressing Turkey to play a larger role against ISIL fighters, who have taken control of large expanses of Syria and Iraq, including territory on Turkey's border, and sent refugees fleeing into the neighbouring country.

The US air force already uses the Incirlik base in southern Turkey for logistical and humanitarian purposes but would need additional authorisation from the Turkish government to launch bombing raids.

A senior Turkish official at the Foreign Ministry told Al Jazeera that the talks focussed on the nature and extent of the planned use of the bases.

He also confirmed that the ways Turkey can help the moderate opposition forces in collaboration with the US is also part of the talks.

He said, however, that there was no deal for moderate fighters to be trained on Turkish soil, denying the earlier international media reports.

Source: Al Jazeera and agencies