Pakistan can do more against terror: Obama

US President Barack Obama has urged Pakistan to show it is "serious" about crushing extremist networks operating on its territory, saying the latest mass killing of students underlined the need for more decisive action.

In an interview with the Press Trust of India published on Sunday, Obama said the crackdown on extremists was "the right policy" but was quoted as saying that Pakistan "can and must" take more effective action.

The US president praised recent crackdowns by security forces but said more should be done to eradicate violent Islamist groups. "Pakistan has an opportunity to show that it is serious about delegitimising, disrupting and dismantling terrorist networks," Obama told the news agency in Washington. "In the region and around the world, there must be zero tolerance for safe havens and terrorists must be brought to justice." Twentyone people were killed last Wednesday in an attack at a university campus in Khyber Pakhtunkhwa's Charsadda town, which was claimed by a faction of the Pakistani Taliban, barely a year after a massacre at the Army Public School in Peshawar that killed 144 people. A military offensive against extremists in tribal areas was intensified after the Peshawar attack, although Indian officials say authorities across the border still turn a blind eye to jihadist groups.