Pakistan's largest refiner Cnergyico will import 1 million barrels of oil from Vitol in October, its Vice Chairman Usama Qureshi told Reuters on Friday, marking the country's first-ever purchase of US crude following a landmark trade deal, Reuters reports.

The West Texas Intermediate light crude cargo will be loaded from Houston this month and is expected to arrive in Karachi in the second half of October, Qureshi said.

"This is a test spot cargo under our umbrella term agreement with Vitol. If it is commercially viable and available, we could import at least one cargo per month," he said, adding that the shipment was not meant for resale.

The deal follows months of multiple negotiations which first began in April, he said, after US President Donald Trump threatened to impose 29% tariffs on imports from Pakistan.

The import deal will help Pakistan diversify its crude sourcing and reduce reliance on Middle Eastern suppliers, who account for nearly all of its oil imports.

Oil is Pakistan's biggest import item and its shipments were valued at $11.3 billion in the fiscal year ended June 30, accounting for nearly a fifth of the country's total import bill.