Iran will award a large contract for the development of phase 19 of the giant offshore South Pars natural gas field in the Persian Gulf within a month, an oil executive said Wednesday.

Iran will award a large contract for the development of phase 19 of the giant offshore South Pars natural gas field in the Persian Gulf within a month, an oil executive said Wednesday.

"It will be awarded maybe within a month or so," Seyed Mehdi Hosseini, a former oil ministry official, who now advises the head of the Iranian Offshore Engineering and Construction Co., or IOEC, told Dow Jones Newswires by phone Wednesday.

"No one knows yet who will be the winner of the tender," Hosseini said.

Iran's natural-gas reserves, second only to Russia's, are estimated at 971 trillion cubic feet. South Pars, the Iranian side of the world's largest non-associated gas field shared with Qatar, where it is known as North Field, accounts for 436 trillion cubic feet.

The Islamic republic has long sought to develop South Pars and held negotiations with Total S.A. (TOT), Royal Dutch Shell PLC (RDSA) and Repsol YPF (REP). However, projects to extract and export gas from the field have been delayed, largely due to sanctions.

Hosseini did not specify which companies bid for the contract to develop phase 19. "No one knows yet who will be the winner of the tender," he added.