DUBAI, United Arab Emirates (AP) — A ship anchored off the United Arab Emirates was seized and taken toward Iran and another — a cargo ship near Oman — sank after being attacked, authorities said Thursday, as tensions escalated near the Strait of Hormuz.

It wasn’t immediately clear who was behind these incidents, but they happened as a senior Iranian official reiterated his country’s claim of control over the waterway and another said it had a right to seize oil tankers connected to the U.S.

The turmoil in the strait, which a fifth of the world’s oil passed through before the war, has been a sticking point for weeks in talks between the U.S. and Iran to end the conflict. Iran’s grip on the vital waterway has jolted the world economy and spiked fuel prices far beyond the Middle East.

Just last week, tensions flared in the strait when U.S. forces fired on and disabled Iranian oil tankers that it said were trying to breach its blockade of Iran’s ports.

The United Kingdom Maritime Trade Operations center said it received reports that the ship seized Thursday was taken by unauthorized personnel while anchored 38 nautical miles (44 miles) northeast of the UAE port of Fujairah, an important oil export terminal that has been repeatedly attacked during the war with Iran.

The U.K. maritime center did not name the ship seized Thursday and said it is investigating. The British military said the vessel is heading toward Iranian waters.

Indian authorities said Thursday that an Indian-flagged cargo ship sank off the coast of Oman after an attack sparked a fire aboard the vessel while it was en route from Somalia to Sharjah, another UAE port. They did not say who attacked the ship.

The attack on the Indian-flagged cargo ship Haji Ali occurred Wednesday, according to Mukesh Mangal, a senior official in India’s shipping ministry. He said all 14 Indian crew members were rescued by Oman’s coast guard and were safe.

India’s foreign ministry called the incident “unacceptable” and condemned continued attacks on commercial shipping and civilian mariners. The ministry did not identify who carried out the attack.

Iran’s judiciary spokesperson told the state-owned Iran Daily newspaper on Thursday that Iran has the legal and judicial right to seize oil tankers in the strait that are connected to the U.S. because the U.S. has violated international maritime laws and committed piracy. The spokesperson, Asghar Jahangir, did not explicitly refer to the tanker seized on Thursday.