Heavily armed Iraqi peshmerga forces reached the Turkish border Thursday and a first small party entered the town of Kobane as they prepared to join fellow Kurds battling jihadists.
The 10 fighters briefly entered Kobane to coordinate with Kurdish militia who have been holding off an assault by jihadists of the Islamic State (IS) group for six weeks, said the Syrian Observatory for Human Rights.
Turkey's Firat news agency said they returned to the town of Suruc on the Turkish side of the border after talks on the logistics of the peshmerga and the weapons crossing the frontier.
A peshmerga convoy reached Suruc Thursday after travelling through southeastern Turkey along roads clogged with flag-waving Kurds, an AFP photographer said.
There it linked up with a second group of peshmerga who had flown in Wednesday, but it was unclear when the main force would cross into Kobane.
Officials have said there are about 150 peshmerga fighters in total, armed with machineguns, heavy artillery and rocket launchers.
The IS jihadists were pounding northern areas of Kobane along the border with mortars and heavy artillery, the Observatory said, in an apparent bid to prevent the peshmerga from crossing.
And they attacked a northern neighbourhood on Wednesday night but were pushed back by Syrian Kurdish People's Protection Units (YPG) militia, said the Britain-based monitoring group.
"The bombardment of the border area will likely delay the entry of the peshmerga" into Kobane, said Observatory head Rami Abdel Rahman, who relies on a wide network of sources inside Syria.
Kobane has become an important symbol of the battle against IS, an extremist Sunni Muslim group that has seized swathes of Syria and Iraq, committing atrocities and declaring an Islamic "caliphate".
- Syria condemns violation -
A US-led coalition carrying out air raids against IS has intensified attacks near Kobane, and the Pentagon said its warplanes made 10 strikes in the area on Wednesday and Thursday.
The coalition carried out two other strikes elsewhere in Syria and two in Iraq, it said.
Washington has also dropped weapons to Kobane's defenders, who had received little in the way of reinforcements until now.
Under pressure from Washington, Ankara agreed last week to allow the peshmerga to cross its territory to Kobane.
Turkey also allowed dozens of lightly armed Free Syrian Army (FSA) rebels to cross into Kobane Wednesday.
An FSA commander told reporters in Turkey it has 400 fighters in Kobane and more on the way.
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Ankara has been wary of giving support to the YPG, which has close links with the outlawed Kurdistan Workers' Party (PKK) that has fought a three-decade insurgency in southeast Turkey.
The peshmerga reinforcements were waiting in a storage facility in Suruc, 10 kilometres (six miles) from the border.
Iraqi Kurdish regional president Massud Barzani, in an online statement, said the Syrian Kurds had said "they did not need combat forces from the peshmerga" but rather "support forces".
"So we decided, in keeping with their request, to send support forces," he said.
Syrian President Bashar al-Assad's regime denounced Ankara, which has long supported the war against it, for allowing fighters to cross the border.
"Once again, Turkey has shown its conspiratorial role... by allowing foreign forces and terrorist groups to enter Syria," a foreign ministry statement said.
"This constitutes a flagrant violation of Syrian sovereignty."
Elsewhere, IS fighters on Thursday seized a gas field in the central province of Homs which has changed hands several times, the Observatory said.
It said the Syrian regime was trying to launch a counter-attack in fighting around the Shaer field.
On the humanitarian front, UN peace envoy Staffan de Mistura proposed setting up so-called "freeze zones" in Syria to suspend fighting in some areas and allow aid deliveries.
- Iraqi forces gather for assault -
On the fight against IS in Iraq, US military chief General Martin Dempsey said American advisers must be sent to its western Anbar province, but that Baghdad must first arm local Sunni tribes.
"We need to expand the train, advise and assist mission into Al-Anbar province, but the precondition for that is that the government of Iraq is willing to arm the tribes," Dempsey told a news conference in Washington.
Norway said it will send about 120 troops to Iraq to help train its armed forces.
Hundreds of Iraqi soldiers and pro-government fighters have gathering for an assault on the strategic jihadist-held northern town of Baiji, officers said.
Baiji lies on the main highway to Iraq's IS-controlled second city Mosul, and the assault could open the way to breaking a months-old jihadist siege of government forces defending Iraq's largest oil refinery near the town.
IS arose in the chaos of Syria's civil war, an uprising that has killed more than 180,000 people and forced millions from their homes in the past three-and-a-half years.