The governor of Afghanistan's most violent province said Sunday that the government controls only eight of its 13 districts.

Helmand Gov. Gulab Mangal said the government has no control in five districts at the northern end of the province and two in the south. He said he hopes Afghan and NATO security forces can implement the rule of law in those regions in coming weeks.

Thousands of U.S. Marines arrived in Helmand last month to help British forces already stationed there to battle militants and extend the government's reach.

Helmand is the world's largest opium-poppy growing region. Drug lords and Taliban militants are believed to earn hundreds of millions of dollars from the trade every year. Mangal predicted that Helmand's poppy crop would drop this year, but didn't say by how much.

Meanwhile, President Hamid Karzai called Iranian President Mahmoud Ahmadinejad on Sunday to congratulate him on his victory in his country's presidential election, Karzai's office said.

Karzai lauded the large turnout and congratulated the Iranian people "for making a decision about their destiny," according to a statement from the presidential palace.

Karzai's phone call comes as opponents of Ahmadinejad challenged the result, saying that reformist Mir Hossein Mousavi — who declared himself the true winner of Friday's presidential contest — had won.

The Afghan president said that relations between Afghanistan and its western neighbor "expanded" during Ahmadinejad's time in office and that he hoped ties would continue to strengthen.

Karzai faces his own electoral fight on Aug. 20, when Afghanistan is to choose among 41 candidates for president. He has won endorsements from most of the country's major political leaders and parties, and most observers see him as the clear front-runner in the country's second presidential vote since the 2001 ouster of the Taliban regime in a U.S.-led invasion.