Turkish warplanes attacked dozens of Kurdish rebel targets in Iraq on Monday as part of a U.S.-backed campaign to chip away at guerrilla strength while avoiding the risks of a ground-based offensive across the border.

The planes hit 70 targets that were "detected and verified by intelligence sources," the Turkish military said in a possible reference to the U.S. intelligence it is receiving.

The Turkish government has fought for more than two decades against Kurdish rebels who seek autonomy in southeastern Turkey. For years, the PKK rebel group has launched attacks into Turkish territory from virtual safe havens in northern Iraq.

The warplanes hit PKK targets in the Avasin-Basyan and Hakurk regions of northern Iraq during a 12-hour operation, the military said on its Web site. "Utmost sensitivity was shown so that the civilian population in the region was not affected," it said.

The reference to civilians reflected a desire to avoid a wider conflict with Iraq's central government or with Iraqi Kurds who suspect Turkey wants to undermine their own separatist tendencies. Washington has pressed Turkey, a NATO ally, to act with relative restraint so that peaceful areas of northern Iraq do not succumb to the upheaval experienced elsewhere in the country.

Turkey has confirmed a total of five aerial attacks inside Iraq since Dec. 16, though Iraqi Kurdish officials have reported other airstrikes.

Turkey's military says its raids have inflicted heavy losses on the PKK, killing up to 175 rebels and destroying command and logistic centers, shelters, and ammunition depots. PKK officials have disputed claims that their operations have been thrown into disarray, and military analysts have speculated that guerrillas dispersed months ago as airstrikes loomed.

As in previous raids, there was no immediate way to independently assess the impact of the latest strike in a remote, mountainous region.

Adem Uzun, a member of the rebel command, said 15 to 20 Turkish jets bombed rebel areas in northern Iraq, according to Firat, a Kurdish news agency. The rebels suffered no casualties, the news agency reported, citing an interview with Uzun by a Denmark-based Kurdish television station.

Senior Iraqi Kurdish officials said earlier Monday that Turkish jets bombed mostly abandoned areas near the towns of Khnera, Khwakurd and Sidakan in Irbil province.

There were no casualties among civilians or Iraqi Kurd fighters known as peshmerga, said Jabbar Yawar, an undersecretary at the ministry governing the peshmerga forces.

The PKK's fight for autonomy has left up to 40,000 people dead over two decades.

The winter is usually a period when rebels rest and resupply before escalating attacks in the spring. Some previous cross-border campaigns by Turkey have hurt rebel strength, but failed to eradicate the group.

The United States and the European Union consider the PKK a terrorist organization. The group is less powerful than in its heyday in the 1990s, but still commands the support of a significant, though possibly dwindling, segment of Turkey's Kurdish population.

The West has urged Turkey to accelerate programs that would help undermine the PKK through non-military means, granting Kurds more cultural rights and promoting economic development in the impoverished southeast, where Kurds constitute a majority of the population. Turkey has taken steps in that direction as part of its effort to join the European Union, but critics say much more can be done.