Turkey has launched a military operation against Kurdish rebels in northern Iraq, hours after the militants killed 24 soldiers and wounded 18 in attacks in southeastern Turkey near the Iraqi border.

News reports quote Turkish officials as saying at least 20 rebels were also killed in the fighting, as Turkish air force bombers hit targets in Iraq and helicopters ferried army troops into the region. Turkish Prime Minister Recep Tayyip Erdogan, who canceled a trip to Kazakhstan, described the action as “hot pursuit” within the limits of international law, following the deadliest such Kurdish attacks in years.

Turkish authorities say rebels from the Kurdistan Workers Party, or PKK, opened fire on military outposts in Cukurca and Yuksekova in Turkey's Hakkari province earlier Wednesday. Kurdish rebels claimed responsibility, prompting President Abdullah Gul to tell reporters that “vengeance for these attacks will be great.”

In worldwide reaction to the raids, U.S. President Barack Obama condemned what he called an “outrageous terrorist attack,” saying the United States will continue its strong cooperation with the Turkish government as it works to defeat the PKK. European Union foreign policy chief Catherine Ashton called the attacks “shameful” and stressed the EU's continued support of Turkey in its fight against terrorism, saying the EU continues to view the PKK as a “terrorist” organization.

In Iraq, Kurdish regional President Massoud Barzani condemned the attacks as a “criminal act.”

Last week, Turkey called on Iraq to stop the Kurdish rebels from attacking Turkey from Iraqi soil, saying its “patience is running out.” Turkish Foreign Minister Ahmet Davutoglu said Ankara is determined to eradicate the rebel threat in northern Iraq.

The PKK has escalated attacks against Turkish targets in recent weeks. Turkish forces have responded by increasing the number of airstrikes against suspected rebel bases in northern Iraq. In August, Turkey's military said it killed as many as 160 Kurdish rebels in air and artillery strikes across the border.

The rebels have waged a campaign for autonomy in Turkey's largely Kurdish southeast since 1984. The conflict has killed more than 40,000 people.

The Turkish government has taken steps to address the demands of Kurds and other minorities for greater rights. Prime Minister Erdogan has been pushing to amend the country's constitution, which was written in 1982 when Turkey was under military rule — a move seen as key to addressing those demands. But Kurdish leaders say an amended constitution should recognize the Kurds as a distinct element of the nation and grant them autonomy.

The PKK is considered a terrorist group by Turkey, the United States and European Union.