Oil prices have dropped today over expectation that higher Iranian exports could add to the already oversupplied market.

Reuters reported that Brent crude dropped 30 cents to $58.21 a barrel, while US futures fell 29 cents to $52.75.

Oil prices went down due to Iran signing a nuclear agreement with six world powers, which will end sanctions imposed by the US, EU and United Nations.

The sanctions that have limited sales of Iranian oil for several years and are now expected to be lifted early next year.

"We view the 2016 prospects for higher OPEC production, including from Iran, as a growing downside risk to our oil price forecast."

Analysts at Goldman Sachs predict Iran to supply an extra 200,000bpd 400,000bpd in 2016 on top of a release of 20 million to 40 million barrels from floating storage.

Estimates by other analysts for Iranian exports changed between 300,000bpd and 700,000bpd.

Goldman expects Brent to trade at $58 in 2015 and $62 next year, while it predicts US crude to average $52 and $57 in 2015 and 2016 respectively.

Analysts at Goldman Sachs said in a note to clients: "We view the 2016 prospects for higher OPEC production, including from Iran, as a growing downside risk to our oil price forecast."

Iran exported around three million barrels per day of crude at its peak prior to sanctions, with shipments reduced to around one million barrels per day in the past two and half years.