Indian Prime Minister Manmohan Singh accused Pakistan yesterday of acting irresponsibly, saying November's Mumbai attacks must have had support from some of its nuclear-armed neighbor's official agencies.

Singh's comments were the latest in almost daily government criticism of Pakistan, and a sign that New Delhi has become increasingly frustrated at what it sees as Islamabad's slowness at identifying and arresting the attack's planners.

India blames Pakistan militants for the coordinated strikes in November by 10 gunmen that killed 179 people and have revived tension between two nations that have fought three wars since 1947. Pakistan denies any involvement by state agencies.