ISLAMABAD, Pakistan (CNN) -- Pakistan is continuing to conduct raids on targets linked to the outlawed group that India blames for last month's massacre in Mumbai, a Pakistani security official told CNN on Monday.

Indian authorities say the sole surviving gunman from the attacks claimed he was trained by Lashkar-e-Tayyiba.

Raids took place Sunday near Muzaffarabad, the capital of Pakistani-controlled Kashmir, the sources said.

A Pakistani military official said 15 people were arrested in the raid but he would not identify any of the suspects until the preliminary investigation has concluded.

It is the first sign of government action against Lashkar-e-Tayyiba, the Islamic militant group India says was behind the killings of more than 160 people in Mumbai, since last month's attacks. iReport.com: Share your reaction to the attacks

Indian authorities say the sole surviving gunman in the attacks has told investigators that he was trained by LeT, which was banned following a 2001 attack on the Indian parliament that brought the nuclear-armed rivals to the brink of war.

Initial reports indicated Zaki-ur-Rehman Lakhvi, a suspected mastermind of the Mumbai attacks, was arrested although it was later denied by CNN sources.

The camp raided was owned by Jamaat-ud-Dawa, a charity formed after the ban. The group says it uses the site as an office for relief work in an area hit by a major earthquake in 2005 but it did not immediately respond to requests for comment Monday.

LeT was formed to fight Indian rule in the divided Himalayan territory of Kashmir, the flashpoint for two of the three wars India and Pakistan have fought since independence.

It has denied any responsibility for Mumbai attacks, and Pakistani authorities deny the attackers were from their country and blamed "non-state actors" for the killings.

India revised the death toll from the attacks downward Monday to 164, including 120 Indian civilians, 26 non-Indians and 18 troops and police officers who died in three days of battles with the attackers. Nine of the gunmen involved in the attacks were killed as well, according to Mumbai police.

U.S. Secretary of State Condoleezza Rice pressured Pakistan to take action against militant groups within its territory during a visit to India and Pakistan last week.

She told CNN's "Late Edition" on Sunday that while there are "historic ties" between the Pakistani government and LeT, "Pakistan is a different place now," with a civilian government working to crack down on militants within its territory.

"We have to remember that Pakistan itself has been suffering at the hands of extremism. So whatever the history here, and there is a history, the important thing is that Pakistan act against those who used Pakistani soil to perpetrate attacks."

CNN's Harmeet Shah Singh and Samson Desta contributed to this report

All About Mumbai • Condoleezza Rice • Pakistan