Turkish sources on Monday denied reports that Ankara had given permission to Washington to use its air bases, particularly that of Incirlik in southern Turkey, to launch strikes on the extremist group "Islamic State" (IS).

"There is no new agreement with the United States about Incirlik," a Turkish government official told AFP news agency.

The official added that negotiations were continuing. Sources from the Turkish prime minister's office also denied any agreement with Washington over the use of bases.

Pressure on Turkey to join in US-led efforts to push back IS militants has intensified as fighting comes to within just hundreds of meters (yards) of the Turkish border.

US officials had said that Turkey had agreed to allow Washington to use its bases, including Incirlik, for its campaign of airstrikes against the jihadists.

Pentagon chief Chuck Hagel said the agreement also included "hosting and conducting training for Syrian opposition members" in Turkey.

Kobani in the balance

Fighting on Turkey's southeastern border meanwhile continued on Monday as Kurdish militiamen defending the northern Syrian town of Kobani engaged in fierce clashes with IS fighters, a day after managing to slow the jihadists' advance.

The fighting around the border crossing to Turkey threatens to cut off Kobani's only remaining lifeline, with the jihadists attacking the town from several directions.

In one attack, an IS suicide bomber detonated a truck laden with explosives in the northern part of Kobani, known officially as Ayn al-Arab, according to Syrian activists based in Britain.

The Syrian Observatory for Human Rights said the vehicle was headed to the border crossing when it exploded.

A Kurdish official in the town said two Kurdish fighters had been wounded in the suicide bomb attack.

Key border town

Kurdish efforts to defend the town are being supported by US-led airstrikes on the militants. The Observatory said there had been at least five strikes early on Monday, mostly targeting Kobani's southern districts.

However, the airstrikes have so far failed to stop the IS extremists as they attempt to seize the town in a bid to consolidate the huge gains they have already made in a sweep across Syria and northern Iraq. Capturing Kobani would give IS control of a long stretch of the Turkey-Syria border.

Pro-government forces in Iraq are also facing intense pressure from IS, with Anbar province and the key oil refinery of Baiji in danger of falling to the militants, who have imposed a harsh version of Islamic rule in the territory they have captured so far.

The group has committed widespread atrocities during its offensive, including attacking civilians, mass executions, beheadings and enslaving women.

tj/shs (AP, Reuters, AFP)