Yemeni officials say at least three soldiers were killed in an operation to root out suspected al-Qaida militants on Saturday, a day after officials announced the death of a radical cleric linked to the terrorist group.

Officials say the soldiers died after clashes erupted during an operation in the volatile city of Zinjibar. Security forces have been trying to regain control of the southern city, which was seized by militants in May.

The raid was conducted a day after U.S.-born cleric Anwar al-Awlaki and several other militants were killed in a suspected U.S. drone strike in Yemen.

Awlaki was wanted in both countries for his suspected role in terrorist attacks and ties to the Yemen-based group al-Qaida in the Arabian Peninsula. U.S. President Barack Obama called his death a major blow to the terrorist group.

The operation also killed Samir Khan, the American editor of an al-Qaida magazine.

In Washington, the U.S. State Department has warned that Awlaki's death has raised the risk of anti-American violence worldwide. A warning issued Saturday says Awlaki's supporters could seek to avenge his death.

The State Department issued a similar alert after Osama bin Laden was killed in Pakistan.

Yemen is also dealing with political turmoil, as anti-government protesters increase their calls for President Ali Abdullah Saleh's resignation.

On Saturday, a Yemeni government spokesman said 1,480 people have been killed this year in clashes linked to anti-government unrest.

The announcement by Deputy Information Minister Abdu al-Janadi marked an unusual admission for Yemen, which rarely provides casualty estimates.

Janadi told reporters in Sana'a the death toll included security forces and civilians who died this year through mid-September.

For months, thousands of anti-government protesters have been taking to the streets with calls for the president's departure. Mr. Saleh's supporters have held counter-demonstrations.