Iran's incumbent President Hassan Rouhani is leading the country's presidential election, Reuters reported citing an Iranian source.

The source said, "It's over, Rouhani is the winner." 

The source also revealed that Rouhani got 21.6 million votes, compared to 14 million for his hardline conservative challenger Ebrahim Raisi, with 37 million votes counted so far. 

CGTN Photo

Rouhani, 68, became president after winning a 2013 election by a wide margin. His desire to engage in diplomacy with Western powers led to a landmark nuclear agreement in July 2015.

In Friday's vote, Iran's Interior Ministry said more than 40 million ballots were cast, indicating a turnout of about 70 percent.

About four million more votes are to be tallied.