Pakistan has arrested more than 130 Islamic militants, including leaders of two groups India blames for an attack last month on its Parliament, an Interior Ministry official said Friday.

Key leaders of Lashkar-e-Tayyaba and Jaish-e-Mohammad militant groups were detained, said Brig. Javed Iqbal Cheema said. No names were immediately available.

"The crackdown which started last night is still going on," Cheema said.

Diplomatic sources said the arrests show Pakistan is serious about defusing tension with India. A summit of South Asia leaders -- attended by Pakistan President Gen. Pervez Musharraf and Indian Prime Minister Atal Bihari Vajpayee -- is scheduled to begin Saturday in Katmandu, Nepal.

Tension between archrivals Pakistan and India worsened after the Dec. 13 attack on New Delhi's Parliament killed 14 people, including five gunmen. India blames Pakistan's spy agency and Lashkar-e-Tayyaba and Jaish-e-Mohammed, both of which recently claimed to have moved their operations to Pakistan-controlled Kashmir, for the Parliament assault.

Pakistan and the two groups deny the accusation.

Both nuclear-equipped countries have massed thousands of troops in the disputed region of Kashmir, where they have fired weapons and artillery at each other across the border. Foreign leaders have implored both countries to find a peaceful solution.

Already in custody for making inflammatory speeches against the government are the heads of Lashkar-e-Tayyaba and Jaish-e-Mohammed -- Mohammed Saeed and Maulana Masood Azhar.

Police and security officials said about 80 of the latest arrests were made in the southern cities of Multan, Behawalpur, Behawalnagar, Rahim Yar Khan, Jhang, Sargodha and Faisalabad. Others were made in the coastal city of Karachi and the border town of Lahore.