U.S. and Arab aircraft resumed bombing raids against positions belonging to the Islamic State of Iraq and Syria (ISIS) in Syria, including oil fields held by the group, Reuters and AFP quoted U.S. officials as saying.
"I can confirm that U.S. military and Arab partner forces are undertaking additional strikes today against ISIL [ISIS] terrorists in Syria," press secretary Rear Admiral John Kirby said in a statement.
Oil facilities held by the militants were among the targets attacked, a senior U.S. defense official, who spoke on condition of anonymity, told AFP.
Reuters said the move appeared to be aimed at stemming the group's cash flow.
An earlier wave of U.S.-led air strikes had prompted Al-Qaeda’s affiliate in Syria, the Nusra Front, and the Islamist militant group, Ahrar al-Sham, to evacuate their bases.
Bases of the Nusra Front in the Idlib countryside, northwest of Syria, were being evacuated, Reuters reported, quoting some of the group’s fighters.
The London-based Syrian Observatory for Human Rights said another group, Ahrar al-Sham, also ordered its followers to evacuate bases.
The early wave of strikes targeted ISIS positions, with one on northwest of al-Qa’im in Syria, two southeast of Irbil in Iraq and two west of Baghdad, the Central Command said in a statement.
The strikes used various attack, bomber and fighter aircraft, and all warplanes were able to leave the area safely afterward, according to the statement.
A Syrian government minister described the strikes as going in the "right direction" because the government was being kept informed and they were not hitting civilians or Syrian military targets.
"What has happened so far is proceeding in the right direction in terms of informing the Syrian government and by not targeting Syrian military installations and not targeting civilians," Ali Haidar, minister for national reconciliation, told Reuters on Wednesday.
Earlier, the Syrian state news agency SANA reported that the coalition had carried out raids near an embattled Syrian Kurdish town and an area on the Iraqi border.
The Syrian Observatory for Human Rights reported 13 air strikes near the town of Albu Kamal.
The Observatory also reported strikes around midnight Tuesday night near Ain al-Arab, known by the Kurds as Kobane, which the Islamic State group has been battling to capture for a week.
The Britain-based monitor said planes crossed into Syria from Turkish airspace and hit ISIS positions and supply lines west of the border town.
But Turkey denied that either its airspace or air bases on its territory had been used in the strikes.
"The answer is clear: Neither the [Turkish] airspace nor the Incirlik [air base] were used," an official told AFP in Ankara.
Incirlik, in southern Turkey, is used by both U.S. and Turkish forces.
Turkey has so far remained hesitant to play an active role in the U.S.-led coalition to defeat ISIS militants, though it has expressed abstract support for its mission.
At least 120 jihadists from ISIS and al-Qaeda in Syria, as well as eight civilians, have been killed in the strikes so far.
The raids around Ain al-Arab come a week after ISIS militants began a fierce assault against what is Syria's third-largest Kurdish town.
ISIS seized at least 64 villages surrounding the strategic town in within days as it advanced towards the town, prompting more than 130,000 civilians to flee into Turkey.
In recent days, Kurdish fighters have managed to slow the jihadist advance.