Saudi Arabia has told Iran it will not permit the use of its airspace or territory for any attack against Tehran, two sources close to the kingdom’s government told AFP on Wednesday, amid warnings from the United States of possible military action.

The message was conveyed as the United States warned it could respond to an Iranian government crackdown on protests, while Tehran has said it would strike U.S. military and shipping assets in the event of a new attack.

"Saudi Arabia has informed Tehran directly that it will not be part of any military action taken against it, and that its territory and airspace will not be used for that purpose," a source close to the Saudi military told AFP.

A second source close to the government confirmed that the message had been communicated to Tehran.

The U.S. has military assets in the Gulf, including in Saudi Arabia.