The Turkish military shelled several Kurdish rebel positions inside northern Iraq on Thursday, an Iraqi security official said.
Turkey has massed tens of thousands of troops along its frontier with Iraq. It has carried out several small-scale cross-border commando operations and aerial bombing raids against rebels of the outlawed Kurdistan Workers Party (PKK).
"They started heavy artillery shelling at about 11 a.m. (0800 GMT). We still don't know if there are any casualties -- the area was deserted except for some PKK members," said Jabbar Yawar, a spokesman for the Peshmerga security forces in Iraq's largely autonomous region of Kurdistan.
He said the shells hit the remote, mountainous area of Hakurk.
But a border guard official posted in the area said he was not aware of any shelling.
Ankara said on Tuesday that Turkey was weighing up a ground operation against the Kurdish rebels, which it blames for the deaths of nearly 40,000 people since the group launched its struggle for an ethnic homeland in southeastern Turkey in 1984.
Turkish Foreign Minister Ali Babacan was quoted by private broadcaster CNN Turk on Tuesday as saying that "the option of a ground operation is on the table".
Earlier this month, Turkish warplanes bombed 70 PKK targets inside Iraq in one of the biggest raids to date and Turkish Prime Minister Tayyip Erdogan vowed to continue the campaign.