DERA ISMAIL KHAN, Pakistan, July 30 (Reuters) - At least 42 people were killed and over 130 injured when a suicide bomber set off explosives at a political rally in Pakistan's northwestern Khyber Pakhtunkhwa province on Sunday, police and rescue officials said. While the TTP and its associated groups have been behind a majority of attacks in Pakistan in recent months, the group distanced itself from Sunday's attack, which its spokesman condemned. Reporting by Saud Mehsud in Dera Ismail Khan and Jibran Ahmad in Peshawar, Pakistan; Nilutpal Timsina; Writing by Gibran Peshimam;Editing by Andrew Cawthorne and Christina FincherAll quotes delayed a minimum of 15 minutes