WASHINGTON, Jan 5 (Reuters) - Communications intercepts collected by the United States confirmed that Islamic State’s (ISIS) Afghanistan-based branch carried out twin bombings in Iran that killed nearly 100 people, two sources familiar with the intelligence told Reuters on Friday.

“The intelligence is clear-cut and indisputable,” one source said.

That source and a second, both of whom requested anonymity to discuss the sensitive issue, said the intelligence comprised communications intercepts, without providing further details. The collection of the intercepts has not been previously reported.

Wednesday’s bombings, the deadliest of their kind in Iran since the 1979 Islamic Revolution, added to regional tensions over the Israel-Hamas war in Gaza and attacks by Yemen’s Tehran-aligned Houthi group on commercial shipping in the Red Sea.