New Delhi, July 17 - A day after his meeting with Pakistan Prime Minister Yousaf Raza Gilani in Egypt, Prime Minister Mahnmohan Signh Friday made it clear that any 'meaningful dialogue' will depend on Islamabad fulfilling its anti-terror pledge 'in letter and spirit.'

The prime minsiter asked Pakistan to take 'sustained, effective and credible action' not only against the perpetrators of the Mumbai carnage, but also against the larger infrastrucure of terrorism on its territory.

'I also conveyed to Gilani that sustained, effective and credible action has to be taken not only against the pertpetrators of the Mumbai attacks, but also shut down the operations of terrorist groups to prevent future attacks,' Manmohan Singh said in a prepared statement he read out in the Lok Sabha within hours of his return.

Manmohan Singh returned here Friday morning after a hectic five-day visit to France and Egypt.