ANKARA, Turkey — Turkish jets struck yesterday at mountain caves that the military said Kurdish rebels were preparing to use as winter hideouts in northern Iraq, the third cross-border air assault in 10 days.

The planes conducted “an effective pinpoint operation” against the separatist rebels of the Kurdistan Workers’ Party, or PKK, the military said in a statement posted on its Web site. However, no rebel deaths from the strikes were immediately reported.

The PKK has waged a war for autonomy in parts of Turkey for more than two decades, a conflict that has cost tens of thousands of lives, and its fighters have bases in Kurdish sections of northern Iraq. Turkey faces domestic pressure to strike back at the rebels, and America and the European Union consider the PKK a terrorist organization.

But America opposes any large-scale Turkish incursion into northern Iraq, currently one of the war-torn country’s most stable areas. The more limited raids conducted recently, including yesterday’s, nevertheless put Washington in an awkward position because Turkey and Iraq are both key American allies.

President Gul said yesterday that Turkey was pleased with American cooperation, including the sharing of intelligence. “It is a cooperation that befits the allies,” he was quoted as saying by the state-run press.

Meanwhile, an earthquake with a preliminary magnitude of 5.5 shook the Turkish capital of Ankara early today, rattling furniture and rousing residents from their sleep, authorities said. There were no immediate reports of injuries.