Iran has cancelled a London conference where it was set to introduce new oil and gas contracts to investors, the Seda weekly reported on Saturday citing a senior Iranian official who blamed a delay in getting visas.
Postponed five times amid uncertainty over international sanctions against Iran which were lifted this month, the conference had been set for Feb. 22-24.
Foreign companies will now be invited in May to bid for the new Iran Petroleum Contracts (IPCs), Ali Kardor, deputy head of the National Iranian Oil Co. (NIOC), told the weekly.
"The London conference has been cancelled because the British embassy in Tehran could not issue visas for representatives of Iranian companies as its visa section has yet to become active," Kardor said.
"There will be bids in May for new contracts ... There will be no need to hold a conference abroad after the bids," he said.
To bolster its economy, Iran is sweetening the terms of its oil development contracts to lure back international companies.
Some 135 firms, including BP (BP.L), France's Total (TOTF.PA), Italy's Eni (ENI.MI) and Spain's Repsol (REP.MC) attended a conference in Tehran in November to hear about the IPC.
Hardline rivals of pragmatist President Hassan Rouhani have criticised the new contracts, however.
The Tasnim news agency said police dispersed a group of 50 protesters, who gathered in front of the Oil Ministry building in Tehran on Saturday to protest against "Rouhani's adopted oil policies and the new oil contracts".
The protesters chanted "Cancel the IPC contracts," Tasnim reported.
Kardor told Seda: "We are in talks with critics to hear their points and to resolve problems when needed."
Some analysts say Rouhani's government is determined to resolve the dispute through diplomacy.
"The oil ministry and the government want a political consensus over this issue ...in a public statement, the government has asked all the experts to express their views," said Tehran-based senior energy analyst Reza Zandi.
International sanctions on Iran were lifted this month as part of a nuclear deal reached with six major powers in 2015 in exchange for curbing Tehran's disputed nuclear work.
OPEC producer Iran has said it now plans to increase its output by 500,000 barrels per day (bpd) and soon by another 500,000 bpd.
A draft of the IPC was approved by the government in September, but the official said the new contract still required approval by the NIOC board of governors.
The IPC would end a more-than-two-decade-old buy-back system that banned foreign companies from booking reserves or taking equity stakes in Iranian companies.