Investing.com -- The U.S. Treasury warned on Friday that shippers paying tolls to Iran for passage through the Strait of Hormuz face potential punitive sanctions, including those making charitable donations to organizations such as the Iranian Red Crescent Society.

The Strait of Hormuz serves as one of the world's most strategically vital maritime routes, with approximately 20% of global seaborne crude oil and liquefied natural gas flows passing through the waterway.

Tehran has proposed implementing fees or tolls on vessels transiting the Strait as part of proposals to end the ongoing conflict with Israel and the United States.

The Treasury's Office of Foreign Assets Control issued the advisory, stating U.S. authorities are aware of Iranian threats to shipping and demands for payments in exchange for safe passage through the Strait.

The warning was released as Iran submitted its latest proposal for negotiations with the U.S. to Pakistani mediators, a development that could enhance prospects for resolving the current impasse in efforts to end the Iran conflict.

OFAC indicated that Iranian payment demands may include multiple options, such as fiat currency, digital assets, offsets, informal swaps, or other in-kind payments. These could include nominally charitable donations made to the Iranian Red Crescent Society, Bonyad Mostazafan, or Iranian embassy accounts.