Turkey on Wednesday launched a military offensive with airstrikes against the Kurdish-administered region of Northern Syria, near its southern border.

Turkish troops started to mass on the Syrian border earlier this week after the White House announced it was pulling United States troops out of the region.

The BBC reported Turkish security forces as saying the start of the offensive would involve airstrikes and artillery fire, and there were reports of explosions in the Syrian frontier town of Ras al-Ayn.

Turkish forces had already crossed the border near the Syrian town of Tal Abyad earlier in the day, The Associated Press reported.

Turkish president, Recep Tayyip Erdogan, confirmed a military operation had begun, with Kurdish forces currently in control of the area reporting airstrikes and "huge panic".

Turkey says it is seeking to establish a 32-km-deep safe zone in the border region to secure the country against the threat of what it says are Kurdish terror groups as well as Islamic State.

In a Twitter post on Wednesday Erdogan said: "Our aim is to destroy the terror corridor which is trying to be established on our southern border and to bring peace to the region."

A spokesman for the Kurdish-led Syrian Democratic Forces, or SDF, said shortly after the announcement that Turkish warplanes had already begun attacking the region, creating a "huge panic among people".

Ankara considers the Kurdish-led SDF an extension of the outlawed Kurdistan Workers' Party and regards their fighters as terrorists, closely linked to Kurdish guerrillas who have waged a long insurgency in Turkish territory.

The US-backed SDF, which did the bulk of the ground fighting against Islamic State in Syria, has been left exposed to a Turkish assault after Trump's announcement that the US would remove the 1,000 special forces posted in the region.

The US forces had acted as a buffer between the SDF and Turkey, a Nato ally to the US and a key trade partner. But The Guardian reported that only around 100-150 US troops had been moved away from key positions on the Syrian-Turkish border.

Trump's decision to pull back US troops from Syria has been widely criticized by some of the president's staunchest Republican allies.

Critics have said the withdrawal risks a humanitarian catastrophe as thousands flee the expected fighting, as well as the reemergence of Islamic State.