James Bays, Al Jazeera's correspondent in northern Iraq, said: "[Goli] is a place that has been a PKK camp, its in a mountainous area, and we believe that attack is about to get under way or is already under way."
With Turkish and Iraq's regional Kurdish government denying journalists access to the clashes are taking place, it is difficult to independently confirm the fighting, he said.
"What is clear from both Turkish and PKK figures, although they're very different," Bays said, "is that there are still casualties on both sides and that heavy fighting is continuing."
The Turkish military says 15 soldiers have been killed since Thursday but PKK fighters say they have killed 47 troops so far.
Turkey also said it had killed 33 more PKK members, taking the Kurdish toll to 112 since the launch of the cross-border incursion on Thursday evening.
The Iraqi government on Sunday called for Turkey to withdraw its troops from northern Iraq.
A statement by Nuri al-Maliki's government urged Turkey "to withdraw its forces from Iraqi soil as soon possible".
"The government of Iraq calls on Turkey to respect its sovereignty and unity and considers that the unilateral operation across the border is a threat to the region," the statement said.
It came after Turkey's military warned Iraqi Kurds not to shelter Kurdish fighters fleeing its offensive.
The PKK is fighting for autonomy in predominantly Kurdish southeastern Turkey and have carried out attacks on Turkish targets from bases in the semiautonomous Kurdish region of northern Iraq.
Started in 1984, the conflict has claimed as many as 40,000 lives.