Investing.com -- Crude and Brent oil futures spiked as much as 5% on Monday following reports that Iran struck a U.S. navy vessel with missiles near the Strait of Hormuz.

Iran's navy said Monday it prevented enemy warships from entering the Strait of Hormuz through swift warnings, according to state television.

The semi-official Fars news agency reported a U.S. warship was struck by two missiles while sailing near the port of Jask at the southern entrance to the strait and turned back from its transit attempt.

A senior U.S. official denied a U.S. ship was hit by Iranian missiles, according to an Axios reporter.

Iran's armed forces issued multiple warnings Monday to foreign navies against crossing into the Strait of Hormuz, threatening a decisive response.

On Sunday, President Donald Trump said the U.S. would begin efforts Monday morning to free ships stranded in the strait as a humanitarian gesture to aid neutral countries in the U.S.-Israeli war with Iran.

Oil futures gave back some gains after the initial spike.