DUBAI, United Arab Emirates — A crude oil tanker in the Persian Gulf caught fire Wednesday night, prompting a warning from British naval officials to “exercise extreme caution.”

The United Kingdom’s Maritime Trade Operations said the fire struck the vessel northwest of Sharjah, an Emirati sheikhdom. It offered no other information.

Emirati officials said they were working to put out the blaze some 21 miles off the coast of Sharjah. They identified the ship as the crude oil tanker Zoya 1 and said 16 Indian and Pakistani crew reportedly had been stuck on the vessel for a year, unpaid, trying to come ashore amid a legal dispute over the vessel.

The state-run WAM news agency later described the tanker as unloaded and said its crew had been rescued.

Officials with the U.S. military said they knew of the fire, but had no further information.

The blaze comes amid heightened tensions in the region after the U.S. killed Iranian Revolutionary Guard Gen. Qassem Soleimani in a drone strike in Baghdad and Iran fired ballistic missiles at Iraqi bases housing U.S. troops.

The U.S. blames Iran for planting mines that exploded against tankers last year near the Strait of Hormuz, the narrow mouth of the Persian Gulf through which 20 percent of all oil passes. Iran denied being involved, though it did seize oil tankers and shoot down a U.S. military surveillance drone.