Kurdish fighters have entered Sinjar in northern Iraq, a day after launching an offensive to retake it from Islamic State (IS) militants.

The Kurdistan Regional Security Council said in a tweet that Peshmerga forces had entered "from all directions" and were clearing the town of IS.

The Kurdish offensive is supported by US-led coalition air strikes.

Meanwhile, the Iraqi army says it has launched an offensive to recapture the western city of Ramadi from IS.

The army press office said the offensive was under way "along the northern, western and south-western axes, with air support", the official al-Iraqiyah TV reports.

However, Reuters news agency quotes a municipal official and a police officer from the area as saying the advance has not yet begun.

'They stole our dignity'

A senior Peshmerga source said Kurdish special forces entered the northern parts of Sinjar and raised the Iraqi Kurdistan flag on a number of buildings, including a primary school, a medical centre and a government office.

But he warned clearing the town "was a work in progress".

"It might take between seven to 10 days to reach the centre... as there is a large scale clean-up operation due to booby traps and suicide bombings, heavily used by IS militants who depend on guerrilla tactics," he told the BBC's Ahmed Maher who is at Mount Sinjar.

The Kurdish news agency Rudaw tweeted a stream of photos and videos it said were of Peshmerga troops inside the town.

"They are patrolling each and every alley of the town and they are repelling [IS militants]. We have seized many of their weapons and we have also bodies of the dead militants. Peshmerga are now in full control of the town," a soldier, Wahder Saleh, said.

The offensive to retake Sinjar began in earnest at dawn on Thursday, with some 7,500 Peshmerga fighters closing in on three fronts after coalition warplanes bombed IS positions, command-and-control facilities and weapons stores.

Within hours, they had successfully blocked Highway 47, the main road between Mosul, to the east, and Raqqa to the west, and secured three surrounding villages.

The Kurds estimated that there were almost 600 IS militants in Sinjar before the offensive began, but the coalition said they believed some 60 to 70 had been killed in Thursday's air strikes.

Thousands from the Yazidi religious minority are reportedly taking part in the offensive. Turkish Kurdistan Workers' Party (PKK) rebels have trained a Yazidi militia, while others have joined the Peshmerga.

IS killed or enslaved thousands of Yazidis when they captured Sinjar in August 2014. Many more became trapped on nearby Mount Sinjar without food or water for days until they were rescued by Syrian Kurdish forces.

The risk of genocide was a key factor in the US decision to launch air strikes in Iraq.

Hussein Derbo, the head of a Peshmerga battalion made up of 440 Yazidis, told the Reuters news agency: "It is our land and our honour. They [IS] stole our dignity. We want to get it back."

Sinjar - a strategic town

--Situated in northern Iraq at the foot of Mount Sinjar, about 30 miles (50km) from the Syrian border

--Highway 47, one of IS's most active supply lines, runs through the town

--Area mainly inhabited by Kurdish-speaking Yazidis with Arab and Assyrian minorities

--Islamic State militants attacked in August 2014

--Some 50,000 Yazidis fled the town and became trapped on Mount Sinjar without food or water

--Since then, Kurdish forces have won back areas of the town but IS resistance has led to a stalemate