Hojjatoleslam Mahmoudi, head of Iran's Islamic Propagation Council, told state media the farewell ceremony would continue for three days and the funeral procession will be announced later.
The official said the public would be able to pay their respects to the body of late Supreme Leader Ali Khamenei at Tehran's Imam Khomeini Prayer Hall starting at 10pm on Wednesday (0530 AEDT Thursday).
"The Mosalla (prayer hall) will be receiving visitors and the dear people can attend and take part in the farewell ceremony and mark a strong presence once again," he said in comments carried by Iranian media.
Khamenei, who based his iron rule of Iran on hostility to the US and Israel, was killed on Saturday, aged 86, in air strikes by Israel and the US, according to Iranian state media.
The body of the slain Iranian religious leader will reportedly be buried in a Shi'ite shrine in his home city of Mashhad.
The Fars news agency, which is close to the Islamic Revolutionary Guard Corps, reported the burial was expected to take place on Tuesday behind the shrine of Imam Reza, similar to Khamenei's father.
The mausoleum to the eighth Imam in Twelver Shia Islam, Iran's state religion, is considered the country's most important Shi'ite shrine.
Mashhad, a metropolis with a population of about three million in the northeast of the country, is the second-largest city in Iran. Khamenei was born there on April 19, 1939.
- with DPA
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