Hundreds of thousands of mourners gathered in Tehran on Saturday as Iran began days of funeral ceremonies for the late Supreme Leader Ayatollah Ali Khamenei, beating their chests in grief as his flag-draped coffin, enclosed in a glass case, passed through the capital.

Crowds also chanted calls for revenge against Israel and the United States.

The funeral for Khamenei, who led Iran for decades before being killed at 86 in a Feb. 28 airstrike during the opening phase of the Iran war, is expected to reinforce the country's ruling theocracy and bolster the authority of its new supreme leader, his son, Ayatollah Mojtaba Khamenei.

The show of unity comes as Iran seeks to strengthen its position in negotiations with the United States over a permanent end to the conflict while concerns persist that Israel could launch further military strikes.

During the ceremony, Iran's chief negotiator also warned France and the United Kingdom against pursuing joint naval patrols in the Strait of Hormuz, the strategic gateway to the Persian Gulf through which about one-fifth of the world's oil and natural gas shipments traditionally pass during peacetime.