RIYADH — Saudi Arabia, the largest producer in the OPEC oil cartel, cannot reduce its output, the kingdom’s oil minister said on Thursday despite plunging prices.

Ali al-Nuaimi added that commodity price fluctuations are to be expected, and he expressed optimism for the future despite crude’s price drop of about 50 percent since June.

“It is difficult, or even impossible, for Saudi Arabia or OPEC to undertake any measure that would lead to a reduction in (their) share of the market and an increase in that of others” who do not belong to the cartel, he was quoted as saying by the official Saudi Press Agency.

“Price fluctuations in commodities, including oil, are normal,” the minister added.

He said he is “optimistic for the future because the situation that we and the world currently face is temporary.”

Crude prices traded above $100 a barrel earlier this year.

They have fallen to multi-year lows since June in the face of a global supply glut, a strong dollar and slower growth in demand.

Prices have plunged even further since last month, when the Organization of Petroleum Exporting Countries decided against cutting production.