Oil prices have fallen below $63 a barrel following news that Greece has failed to make a loan repayment to the International Monetary Fund (IMF), leading to a gain in dollar value.

Brent crude dipped 70 cents at $62.89 a barrel, while the US crude fell 89 cents to $58.58, Reuters reported.

Prices were dragged down by an increase in the production by the US and Organization of the Petroleum Exporting Countries (OPEC), prompting oversupply concerns.

"Greece is an additional risk factor, but I am more focused on Vienna than on Athens right now."

Oil weighed down following the report released by the American Petroleum Institute (API), which revealed that there is an increase in the US crude oil inventories.

The prospect of Iranian oil exports reaching an oversupplied market also led to a drop in prices.

Iran is holding discussions with world powers in Vienna with regard to their nuclear deal, for which the deadline has been extended until 7 July.

Petromatrix oil analyst Olivier Jakob told the news agency: "Greece is an additional risk factor, but I am more focused on Vienna than on Athens right now."

Other currency holders could find it expensive to buy commodities like oil due to a stronger dollar value, which in turn would weigh oil prices.

A survey by Reuters on Tuesday revealed that OPEC supply increased to a three-year high of 31.60 million barrels per day last month.

Another poll by Reuters also found that Iranian export could soar about 60% within a year if the nuclear deal is clinched with world powers.