The data showed Iran shipped more than two million barrels per day so far in April, compared to around 1.45m barrels a day in March.
Iran has been squaring off with oil cartel Opec defacto leader Saudi Arabia in recent days as the worlds biggest oil producers prepare for a meeting in Doha on Sunday to hash out a deal to freeze output.
The oil price moved marginally lower on the news, falling by 0.7 per cent to $44.34 per barrel of Brent crude. US Texas Light Sweet was trading around $41.86 in the late afternoon market.
Iran has said it is committed to increasing its production back to pre-sanction levels to regain market share it lost due to a trade embargo that lifted in January.
Saudi Arabia meanwhile has refused calls to cut production to prop up the oil price amid fears its own market share will decrease.
Smaller oil producing nations have seen their economies shattered due to the 60 per cent slump in the oil price since mid 2014.
A decline in expensive US shale oil production has lowered the importance of the meeting, with the International Energy Agency expecting the glut in the market will fall to 0.2m barrels per day in the second half of this year, down from 1.5m barrels from January to June.
"The oil market looks set to move close to balance in the second half of this year. Oil prices are on the rise with Brent crude oil trading currently well above $40 per barrel," the IEA said in its monthly report.