Syria (BBN)-New air strikes have targeted Islamic State (IS) militants in Syria, hitting areas close to the border with Turkey.
Syrian activists reported strikes around the Kurdish town of Kobane, which has been besieged by IS fighters for several days, reports BBC.
Witnesses saw two military aircraft approaching from Turkey but Turkish officials denied its airspace or bases were used in the attack.
The US-led coalition expanded its raids against IS into Syria on Monday.
But the aerial bombardment near Kobane, which happened at about 01:00 local time (22:00 GMT), has not been confirmed by the US or any coalition member.
Turkish military sources said neither its air force nor the US airbase at Incirlik in southern Turkey had been used.
Overnight, US Central Command (Centcom) confirmed it had conducted two more strikes in Syria, hitting two IS vehicles in Deir al-Zour in the east of the country.
IS has seized large areas of Syria and Iraq, and the US has launched nearly 200 air strikes in Iraq since August.
Meanwhile, the BBC understands that the UK Parliament will be recalled on Friday to discuss Britain's possible role in air strikes on IS targets.
Speaking on Tuesday, UK Prime Minister David Cameron said an international coalition was needed to "destroy" IS, adding that it was a fight "you cannot opt out of".
The Dutch government is also considering military action and will hold a special cabinet meeting on Wednesday to discuss deploying four F-16 fighter jets.
REFUGEE CRISIS
The IS advance in northern Syria has created a refugee crisis in neighbouring Turkey.
Aid agencies said some 130,000 Kurdish refugees, most of them from Kobane, crossed the border at the weekend.
Turkey had initially refused to take part in military action against IS, but President Recep Tayyip Erdogan signalled a possible change in policy on Tuesday.
"We will give the necessary support to the operation. The support could be military or logistics," he told reporters in New York, where he is attending the UN General Assembly meeting.
Correspondents say Turkey may be willing to get more involved after it secured the release of 49 Turkish hostages who had been held by IS militants in northern Iraq.
The BBC's Mark Lowen, who is on the Syria-Turkey border, says Kurds still in Kobane reported a significant increase in shelling by IS militants on Wednesday morning.
A Kurdish military commander told Reuters news agency that IS boosted its forces after the air strikes, sending extra fighters and tanks to the outskirts of Kobane.
'LONG BATTLE AHEAD'
On Tuesday, Pentagon spokesman Rear Adm John Kirby said the US strikes in Syria had disrupted IS but warned that the right against them would take years.
"It's going to take a serious effort by all involved. We do believe that we're talking about years here," he told the BBC.
US President Barack Obama hailed the support of Arab nations in air strikes against IS on Monday, saying: "This is not America's fight alone."
The US said Saudi Arabia, the United Arab Emirates, Jordan, Bahrain and Qatar had all "participated in or supported" the strikes.
BBN/ANS-24Sept14-5:30pm (BST)