Speaking at a televised program on Saturday, Rahmani Fazli said the Guardian Council has decided that a runoff parliamentary election be held on April 17.
If the turnout in the February 21 election is high, fewer regions will have to hold a runoff voting, resulting in a reduction in the costs, the minister added.
He also noted that 54,611 polling places across the country will open on Friday in 208 electoral regions, saying the ballot papers have been designed with 10 security indices to prevent any fraud.
According to the interior minister, there are 57,918,159 eligible voters in the parliamentary elections on Friday, including around 3 million people eligible to vote for the first time.
The election campaigns officially began in Iran at 00:00 Thursday (20:30 GMT, Wednesday), and will last until the end of February 19.
The nationwide votes for the parliament and the midterm election of the Assembly of Experts will be held simultaneously on Friday, February 21.
The campaigns for the Assembly of Experts midterm election had already begun on February 6.
A total of 7,148 candidates, including dozens of Iranians from the religious minorities, are running for the parliament. There are 290 seats in the parliament up for grabs.
In capital Tehran, 1,453 candidates are contesting one of the 30 allocated seats on the legislature.
The lawmakers are elected for a 4-year term, with no limitation for the incumbent or former parliamentarians to run again.
Also people in five provinces, North Khorasan, Khorasan Razavi, Fars, Tehran and Qom are going to elect 7 candidates running for the midterm election of the 88-member Assembly of Experts, a high-ranking body that elects leader of the Islamic Revolution.
Members of the assembly are directly elected to office by people for an eight-year term. It holds biannual meetings to appoint a new chairman.
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