Presidential candidate Hassan Rohani casts his ballot during the Iranian presidential election in Tehran June 14, 2013. [Photo/Agencies]

TEHRAN - Iran's interior minister says preliminary election returns give reformist-backed candidate Hasan Rowhani a significant lead in the presidential race.

The minister, Mostafa Mohammad Najjar, said Saturday on state television that Rowhani has nearly 402,000 votes out of a total of 861,866 counted.

That gives the former nuclear negotiator an early wide margin over Tehran Mayor Mohammad Bagher Qalibaf, with about 126,000 votes, and nuclear negotiator Saeed Jalili, with about 119,000.

It was unclear when final results would be known. Iran has more than 50 million eligible voters, and turnout was believed to be high.