BEIRUT, Lebanon — Charges that four oil vessels were attacked at the mouth of the Persian Gulf over the weekend have amplified fears across the region about the escalating tensions between Iran and the West.

The unconfirmed reports come as the United States has tightened sanctions against Iran and mobilized an aircraft carrier, bombers and an antimissile battery to the gulf to deter what the Trump administration has said is a heightened risk of Iranian aggression.

Saudi Arabia said Monday that two of its oil tankers had been sabotaged, and a Norwegian company reported that one of its tankers was damaged in the same area, near the Strait of Hormuz. The fourth ship belonged to the United Arab Emirates, which, like Saudi Arabia, is an avowed enemy of Iran.

Neither Saudi Arabia nor the United Arab Emirates assigned blame, made public any evidence of damage to their ships or described the nature of the sabotage.