A U.S. warship has rescued six Iranian mariners after their vessel broke down in waters off the coast of Iraq.

Pentagon officials say a U.S. Coast Guard cutter responded to distress calls early Tuesday morning about 90 kilometers from the Iraqi port city of Umm Qasr.

The Iranians said their ship was taking on water. It is unclear how the six will be repatriated to Iran.

Last week, U.S. Naval forces rescued 13 Iranian fishermen held by pirates in the north Arabian Sea.

The rescues come as tensions worsen between Iran and the West about objections to Iran's controversial nuclear program and threats from Tehran to close the strategic Strait of Hormuz.

Western nations have sought to increase pressure on Iran about the program, saying it is aimed at developing nuclear weapons. Iran insist its program is for peaceful purposes.