GENEVA/DUBAI (Reuters) - The top military adviser to Iran’s Supreme Leader Ayatollah Ali Khamenei said on Wednesday that Tehran would not negotiate with the United States under any circumstances, an apparent hardening of its position as the Gulf tanker crisis escalates.

FILE PHOTO: Iran's Supreme Leader Ayatollah Ali Khamenei speaks during ceremony attended by Iranian clerics in Tehran, Iran, July 16, 2019. Official Khamenei website/Handout via REUTERS

The Swedish operator of a British-flagged oil tanker seized by Iran in the Gulf last week said it had been able to speak to crew members and all 23 of them were safe.

“We had direct contact with the crew on board the vessel last night by telephone and they’re all okay and in good health and they’re getting good cooperation with the Iranians on board,” Stena Bulk spokesman Pat Adamson said.

The company said it had no evidence that the ship had been involved in a collision, one of the reasons Iran has cited for sending commandos to capture it last Friday.

The tough remarks by Khamenei’s aide, Hossein Dehghan, a senior commander of Iran’s elite Revolutionary Guards whose views are seen as reflecting those of Khamenei, appeared to take a firm line in response to Western proposals to beef up security in the Strait of Hormuz in the wake of the seizure of the ship.

Dehghan said Iran would take action if the status of the strait were altered, and that no country would be allowed to ship oil through it unless all countries can.

His remarks were reported by Al Jazeera television which did not supply direct quotes of an interview with him. He singled out the United Arab Emirates for criticism, saying it had become a base for attacks on Iran, and repeated earlier Iranian threats to attack all U.S. targets in the region in the event of war.

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Dehghan’s remarks appear to shift the Iranian position on talks with the United States. In the past Tehran has said talks are possible although Washington must lift all sanctions first and return to the nuclear deal it abandoned last year.

The Trump administration says the purpose of its sanctions is to force Iran to the negotiating table, and it is open to talks, but Iran must make the first move.

Earlier on Wednesday, Iran’s pragmatist president, Hassan Rouhani, who has drawn fire from hardline clerical leaders for reaching the nuclear pact with world powers in 2015, said Iran was ready for “just negotiations” but not if they mean surrender.

Britain has called for a European-led naval mission to ensure safe shipping through the world’s most important oil artery after Iran seized the Stena Impero last week. The United States is trying to rally support for a global coalition to secure Gulf waters, although allies have been reluctant to join a U.S.-led mission for fear of escalating confrontation.

France, Italy and Denmark gave initial support to the British plan. A German Foreign Ministry spokesman said Berlin was talking to Britain and France about the idea.

The Trump administration abandoned the nuclear deal last year arguing that it was too weak because it did not cover non-nuclear issues such as Iran’s missile program and its regional behavior. Dehghan repeated Iranian assertions that its missile program is non-negotiable.