Moderates and reformists are poised to take control of parliament in Iran after strong gains at run-off elections, early results suggest.

Preliminary results show politicians allied with reformist President Hassan Rouhani won half of the 68 seats being contested on Friday.

With the support of independents, they are assured of a working majority, a BBC correspondent reports.

February's first round gave them 106 of the parliament's 290 seats.

In the run-off, held in constituencies where no candidate had won the minimum 25% of the vote, Rouhani allies took 34 seats and hardliners 12, early results indicate.

On the same basis, most of the remaining seats went to independents, with four still to be declared. Official results are expected on Sunday.

The preliminary results mean that reformists are poised to wrest control of parliament from hardliners for the first time since 2005.

They are an endorsement of the nuclear agreement that the government of President Rouhani signed with the US and other world powers to curtail Iran's nuclear programme in return for the lifting of international sanctions, BBC Persian TV's Kasra Naji reports.

This is in spite of the fact that the economic benefits of the agreement have been slow in coming, our special correspondent adds.

'Issue by issue'

In February, reformists also made gains in elections for the Assembly of Experts, which appoints the country's most powerful official, the Supreme Leader.

Dr Sanam Vakil, an associate fellow at Britain's Chatham House think tank, said the swing power of independent lawmakers would make for combative politics in Iran.

"It's going to be issue by issue," she told Reuters news agency.

"I don't think we should expect a group of independents to be supportive of any political, social and cultural liberalisation."

Analysts say that although the parliamentary elections are not expected to herald large-scale changes in Iranian policies, they could help President Rouhani push through economic and social reforms.