NEW DELHI/ISLAMABAD (Reuters) -India is considering plans to dramatically increase the water it draws from a major river that feeds Pakistani farms downstream, as part of retaliatory action for a deadly April attack on tourists that New Delhi blames on Islamabad, according to four people familiar with the matter. Delhi "put in abeyance" its participation in the Indus Waters Treaty of 1960, which governs usage of the Indus river system, shortly after 26 civilians in Indian Kashmir were killed in what India called an act of terror. Pakistan has denied involvement in the incident, but the accord has not been revived despite the two nuclear-armed neighbours agreeing a ceasefire last week following the worst fighting between them in decades.