Polls have opened in Iran's parliamentary runoff elections, a key vote to decide whether hard-liners or moderate forces backing President Hassan Rouhani will control the legislature.

Iranian state television reported polls opened at 8 a.m. Friday. They will remain open until at least 6 p.m., though election hours often get extended.

Nearly 17 million Iranians are eligible to vote in 55 cities and towns. They will decide on 68 candidates for the 290-seat chamber.

In February, a bloc of reformists and moderate allies of Rouhani won a majority. The bloc needs to win 40 seats to control the parliament, which begins work in late May.

The results of the February elections were seen as a major setback for hard-liners opposed to the landmark deal reached with world powers last year.