The United Arab Emirates' daily oil output is down by more than half as the Iran conflict and the effective closure of the Strait of Hormuz forced state oil giant ADNOC to implement widespread production shut-ins, two sources told Reuters.

The halt of commercial navigation through the critical maritime chokepoint, normally used to transport about a fifth of the world's oil supply, has inflicted massive disruptions on global energy markets.

Earlier today, ADNOC halted oil loading operations at the UAE's port of Fujairah, a major oil bunkering and storage hub, due to a drone attack. Operations had just resumed on Sunday following a separate attack over the weekend.

The UAE produced just under 3.4 million barrels per day in January, or more than 3% of global demand, according to secondary sources reporting to the Organisation of the Petroleum Exporting Countries (OPEC), of which the UAE is the third-biggest producer.

Widespread Middle East oil production halt

The two people familiar with the matter said the shut-ins — temporary well closures — affected both onshore and offshore production. They asked not to be named due to the sensitivity of the matter.

Read More: Why does the port of Fujairah matter to the oil market?

ADNOC had said it is cutting offshore production, and sources have said all offshore production is now offline.

Before the war, ADNOC exported just over 1m bpd of Upper Zakum crude, just under 700,000 bpd of Das Blend and about 230,000 bpd from the Umm Lulu field, Kpler data on offshore production showed.

Exports of onshore Murban crude had jumped to about 1.5m bpd in February from 1.135m bpd in January, Kpler data showed.

Saudi Arabia, OPEC's top producer, has cut production by about 20%, Reuters has reported. Iraq, OPEC's second-biggest member, has slashed output by some 70%. Total oil output cuts in the Middle East now stand at 7-10m bpd, or 7-10% of global demand, according to analysts' estimates.