OPEC wants to see stability in the international oil market, stressing low prices can have a negative effect on long-term investments, the cartel said. Oil prices have declined since highs early this year. Iranian threats to close key shipping lanes through the Strait of Hormuz sent oil prices soaring to more than $100 per barrel, though recent concerns over the European economy have dragged on prices during the second quarter. Members of the Organization of Petroleum Exporting Countries met in Vienna with European counterparts to discuss the oil markets during a time of economic uncertainty. Kuwaiti Oil Minister Hani Abdulaziz Hussain, an OPEC readout stated, said economic uncertainty \"particularly in the eurozone\" was the reason for much of the volatility in crude oil prices. Sanctions targeting the Iranian energy sector go into force in a matter of days. The International Energy Agency, however, said oil markets are well-supplied. European Energy Commissioner Gunther Oettinger said he was concerned high oil prices would hurt any chance of economic recovery while OPEC Secretary-General Abdalla Salem el-Badri said low prices would \"break the momentum of investment.\" OPEC, during its regular meeting in Vienna in mid-June, opted to keep production quotas in place despite slumping crude oil prices.