Asian imports of Iranian crude rose 12% in April from the previous month to a four-month high of almost 1.2mn barrels per day (bpd), topping a level allowed under economic sanctions aimed at Tehran’s disputed nuclear programme.

Still, for the first four months of the year imports were only slightly above the 1mn-bpd threshold, suggesting Iran’s oil exports are unlikely to ruffle feathers as negotiators prepare for talks this month on a final agreement that will end the sanctions in exchange for Iran accepting curbs and checks on its atomic activities.

Imports by Iran’s four biggest buyers – China, India, Japan and South Korea – totalled 1.17mn bpd last month, down 4.1% on year and the highest since hitting 1.21mn bpd in December, government and tanker-tracking data showed.

Iran, the US, Britain, France, Germany, Russia and China reached a tentative framework for a nuclear pact on April 2 but several issues remain unresolved. They have a self-imposed June 30 deadline to arrive at a comprehensive agreement.

US Energy Secretary Ernest Moniz will join US Secretary of State John Kerry for negotiations with Iranian officials in Geneva today as momentum builds for an agreement. But any early surge of oil exports is seen as unlikely.

“There should be enough momentum now. Another extension seems unlikely so a deal on June 30 or shortly after seems more likely than not right now,” Torbjorn Soltvedt, analyst at Verisk Maplecroft for the Middle East and North Africa, told Reuters Global Oil Forum this week.

“Full lifting of oil sanctions from mid-2016 seems likely,” Soltvedt said.

Iran is keen to recover market share lost under the US and European Union sanctions that have curbed its exports to around 1mn bpd from 2.5mn bpd in 2011.

Those concerns did not stop Iranian foreign minister from warning on Thursday that a deal would be hard to achieve if there are “excessive demands” from other parties. He spoke after France warned on Wednesday that it was ready to block a final breakthrough deal unless Tehran provided UN nuclear inspectors access to all installations, including military bases.

Iran rejects Western suspicions that it has covertly sought to develop nuclear arms capability as part of its uranium enrichment drive, saying it seeks only peaceful atomic energy.

Until the final deal is reached on Tehran’s nuclear activities, of its four Asian buyers, only China is likely to increase imports significantly, sources have said.

China’s April imports from Iran were at an 11-month high and well above the 2014 average of roughly 550,000 bpd, about the same level as before the US and the European Union tightened sanctions over Iran’s nuclear programme in early 2012.

Lower purchases this year from India, which revived imports after a one-month hiatus in March to avoid US pressure, helped to keep Iran’s shipments at levels acceptable to Washington.