Iran has discovered a massive onshore gas field in the country’s south after a year of exploration, Fars news agency reported on Wednesday.

The find was made in a reservoir 3,900 meters below the earth’s surface. The site is estimated to house enough energy to power all homes in Tehran – a city of more than 12 million people – for 16 years, the report said.

“This field was discovered after a year of continuous exploration in southern Iran,” head of exploration at the National Iranian Oil Company (NIOC) Saleh Hendi told Fars.

More detailed information about the land-based hydrocarbon discovery will soon be announced by the NIOC managing director, the news agency added.

Hendi also confirmed the discovery of new oil reserves in the southwestern Dezful region, first announced in August.

The reservoir was found in the Ilam and Gurpi formations which are extended in the provinces of Khuzestan, Lorestan and Fars.

The Gurpi Formation is one of the most important lithostratigraphic units in the Zagros foreland basin because of its significance in the petroleum geology of Iran as the source rock.

Iranian officials have said the country is pressing ahead with its energy development plans despite intensified US sanctions which seek to cripple the country.

Last December, Hendi said some 35-40 new hydrocarbon reservoirs had been discovered across Iran, which needed development. “We are now ranked first in the world for oil and gas reserves," he said.

Hendi also said Iran was scouring 60 percent of its total area for new oil and gas reserves, including in places which were deemed until recently the least likely to have hydrocarbon-bearing formations.

In January, the country struck oil in Abadan, containing reserves of “very light and sweet”. The discovery on Minoo Island was the first ever oil find in the general area of Abadan which is home to Iran’s largest and oldest oil processing facility.

President Donald Trump has described Iran as a country of "tremendous potential”, but ruled out lifting unilateral US sanctions on Tehran.

Iran's Minister of Petroleum Bijan Zangeneh on Tuesday admitted that the sanctions have led to the country's oil industry falling behind but Tehran will resist.

“The conditions in Iran are in a way that once every few years the oil industry receives a deadly blow and the economic sanctions can be considered one of those,” he said.

“This has caused Iran’s oil industry to fall behind from the international position and space but we will resist in this area,” Zangeneh added.

The minister said talks were underway with several domestic companies to extract more oil from South Pars, but they had not come to a conclusion yet.

South Pars is the world’s largest gas field, but it also has significant oil reserves which Iran shares with Qatar across from the Persian Gulf.

Zangeneh said China’s national petroleum company CNPC had pulled out of developing phase 11 of South Pars and the project had been awarded to NIOC subsidiary Petropars.

"China has pulled out of developing the phase 11 of the South Pars field and Petropars will carry out the job,” he said.

Petropars signed a $440 million contract last month to produce 500 million cubic feet per day of gas from the Belal field in the Persian Gulf.

"Despite US sanctions, the train of the oil industry development has not stopped ... sanctions have not stopped us; we are alive; we are active and are making efforts for the sake of Iran's oil industry," Zangeneh said at the signing of the contract.

On Tuesday, the minister said Iran also plans to begin operation at Farzad B gas field and its contract will be signed in the coming months.

Indian companies discovered the Farzad B gas field in Iran in 2008 and had bid several times for its development. But each time they either dragged their feet at the time of sanctions on Iran or made financial proposals unacceptable to Tehran when those sanctions were lifted.