Iran's hardline parliament speaker registered on Monday for the country's June 28 presidential election, the last day for aspirants to enter the race.

The entry of Mohammad Bagher Qalibaf brings a prominent candidate with close ties to the country's paramilitary Revolutionary Guard into the vote to replace President Ebrahim Raisi, who died in a helicopter crash with seven others on May 19.

The election comes at a time of heightened tensions between Iran and the West over Tehran's rapidly advancing nuclear programme, its arming of Russia in that country's war on Ukraine and its wide-reaching crackdowns on dissent. Meanwhile, Iran's support of militia proxy forces throughout the wider West Asia have been in increased focus as Yemen's Houthi rebels attack ships in the Red Sea over the Israel-Hamas war in the Gaza Strip.

Qalibaf, 62, initially became speaker following a string of failed presidential bids and 12 years as the leader of Iran's capital city, during which he built onto Tehran's subway and supported the construction of modern high-rises. He was recently re-elected as speaker.

Many, however, know Qalibaf for his support, as a Revolutionary Guard general, for a violent crackdown on Iranian university students in 1999. He also reportedly ordered live gunfire to be used against Iranian students in 2003 while serving as the country's police chief.