"The order to pay the IMF has been executed," a senior Greek finance ministry official said.
Athens is close to running out of cash and there had been doubt about whether it would pay the IMF or choose to save cash to pay salaries and pensions later this month. Greece's government in recent days had insisted it would honor its obligations, but officials in the past have warned the country may not have enough money to make the payment.
Despite the payment, Greece's financial condition remains precarious unless it secures fresh aid from lenders.
Greek officials were pressing euro zone finance ministers at a meeting in Brussels on Monday to acknowledge progress in talks with lenders on a cash-for-reforms deal, in the hope it will pave the way for some token to ease the cash crunch.
Arriving for the meeting, Greek Finance Minister Yanis Varoufakis told reporters he expected a deal to be struck "in the next few days."
"Deadlines by necessity are inflexible, but there are red lines and the red lines are such that there is common ground," he added.