Turkish military officials say five soldiers and at least 44 Kurdish rebels have been killed since a Turkish ground offensive into northern Iraq began late Thursday. Ankara accuses Kurdish Workers Party separatists of using bases in Iraq to launch attacks against government troops in Turkey.

Turkish forces backed by fighter planes and helicopters continued their operation against bases of the Kurdish Workers Party (PKK) in northern Iraq Saturday.

In a statement, the Turkish army said at least 44 Kurdish rebels and 5 soldiers had been killed in the fighting. The PKK says it killed 20 Turkish soldiers.

The conflicting claims could not be independently verified because of the mountainous and sparsely populated region where the fighting occurred.

In a statement on Friday Turkish Prime Minister Recep Tayyip Erdogan said the incursion has limited goals.

Mr. Erdogan said this operation is to protect the Turkish people. He said once the military achieves its goal of destroying the PKK's logistical and psychological support, the forces will withdraw.

Mr. Erdogan said he had informed President Bush ahead of the operation.

No official figure has been given on the size of the incursion or its duration, although Turkish media reports claim up to 10,000 soldiers have entered Iraq.

But a statement by the Turkish army released on its web page criticized the media for exaggerating the number of soldiers involved, claiming it has caused unnecessary international tension.

Pressure is growing on Turkey amid concerns the incursion could destabilize Iraq. U.S Secretary of State Condoleezza Rice advised caution.

"Stability and progress for Iraq is in the interests of Turkey and so everyone should keep in mind that nothing should be done to destabilize what is a fragile but improving situation in Iraq," she said.

But Turkey claims the operation is necessary ahead of an expected spring offensive by the Kurdish rebels. Ankara says up to three thousand PKK members are using the semi autonomous Iraqi Kurdish enclave as a base to launch attacks against Turkey.

The PKK has been fighting for autonomy in Turkey's mainly Kurdish southeast since 1984. Last autumn, about 50 Turkish soldiers and civilians were killed in a spate of PKK attacks. Until now Turkish operations against the rebels has been largely confined to air strikes, aided by U.S. intelligence. But with Turkish soldiers entering Iraq there are fears that the conflict could involve Iraqi Kurdish forces. Iraqi Kurds are a valuable U.S. ally. Pressure is expected to continue to mount on Turkey to end its operation as soon as possible.