"Can it go any lower?" the International Energy Agency asked in its monthly oil market report.
"Unless something changes, the oil market could drown in over-supply. So the answer to our question is an emphatic yes. It could go lower."
The oil price this week hit lows not seen in 12 years, and is currently trading at or below 29 dollars per barrel.
Iran's return to the oil market, a major reason for continued price weakness, has probably not been fully factored into prices yet, the IEA warned, contradicting many financial analysts.
Iran is facing "the not inconsiderable challenge" of finding buyers willing to take more oil into an already glutted market, the IEA said.
"However, if Iran can move quickly to offer its oil under attractive terms, there may be more 'pricing in' to come," it said.
Even under the sanctions regime, Tehran did everything it could to ensure the country's oil sector is prepared for higher output as it strives to reclaim its spot as OPEC's second biggest producer after Saudi Arabia, a post now occupied by neighbouring Iraq, the IEA added.
These production cuts are the only "bullish side" for the oil market, the IEA said, with most other factors conspiring to keep the oil price under pressure.
Growth in world demand for oil, which rose more than most years this century in 2015 before being drowned in over-supply, is expected to ease off.
Worldwide demand for oil is now expected to rise by 1.3 percent in 2016 to 95.7 million barrels of oil, a sharp slowdown after a 1.8 percent increase in 2015.
