Mr. Khan, a former cricket star, has staged a comeback since being ousted, openly challenging the powerful military. His detention raises fears of mass protests.
Supporters of the former prime minister of Pakistan have repeatedly clashed this week with the security forces, keeping the country on edge. “Show you can fight,” he told supporters.
At least one unidentified man opened fire on Mr. Khan’s convoy while he was leading a protest march to the capital, Islamabad. Mr. Khan was wounded in the leg, in what aides said was a targeted attack.
The decision by Pakistan’s election commission is a major escalation of the showdown between the ruling establishment and Mr. Khan, and it raises the specter of unrest.