Iran has presented a new model for oil field development contracts, aiming to tempt back foreign energy companies, Iranian media reported.

One change under the new integrated petroleum contract (IPC) will allow foreign contractors to work on fields over the long term instead of having to hand them over at an early stage to Iranian companies.

Under Iran's former "buy back" system, contractors did initial development work and then were paid in oil, which proved unpopular with foreign investors before Western sanctions drove them away.

Mehdi Hosseini, head of a committee revising that system, told a forum in Tehran on Sunday that approach was too one-sided and only benefited Iran.

Investors will also be offered better terms for riskier projects, as in neighbouring Iraq, whose contracts Iranian officials drew from.

"In the new contracts, different stages of the petroleum industry (exploration, development and production) are awarded in an integrated manner," Hosseini was quoted as saying by the Shana oil ministry news service.

"We must try to persuade foreign companies to enter high-risk zones of the petroleum industry," he said, adding that the government should not shoulder the high costs of exploring for oil and gas but should ensure contracts reward those who do.

Some oil majors are waiting for multi-million dollar payments for projects completed decades ago.

Western sanctions on Tehran over its nuclear programme have also made it difficult to get oil and choked Iran's output over the last two years.

An interim deal between Western powers and Tehran has eased some trade restrictions, but bans on US or European companies making long-term investments in the country remain in place. - Reuters