Iran’s support for international terrorist groups remained undiminished last year and even expanded in some respects, the Obama administration said Friday, less than two weeks before the deadline for completing a nuclear deal that could provide Tehran with billions of dollars in relief from economic sanctions.

The assessment offered a worrying sign of even worse terror-related violence to come after a year in which extremists in the Middle East, Africa and Asia committed 35 percent more terrorist acts, killed nearly twice as many people and almost tripled the number of kidnappings worldwide. Statistics released by the State Department on Friday also pointed to a tenfold surge in the most lethal kinds of attacks.

Yet even as the Islamic State and the Taliban were blamed for most of the death and destruction in 2014, the department’s annual terrorism report underscored the ongoing threat posed by Iran and its proxies across the Islamic world and beyond.