Pakistan, July 4 -- Thousands of mourners gathered in Tehran on Saturday as funeral ceremonies for Iran's late Supreme Leader, Ali Khamenei, officially began, with authorities expecting millions to participate in commemorative events over the coming days.

Read More: Iran begins week of public mourning and funeral ceremonies for Ayatollah Khamenei

According to Iranian officials, between 15 and 20 million people are expected to attend ceremonies in the capital during a week of mourning intended to demonstrate national unity and resilience. Khamenei, who led Iran from 1989 until his death at the age of 86, was killed on February 28 during US and Israeli strikes, according to Iranian authorities.

Large crowds carrying red flags, symbolisin...