Fifteen British sailors and marines freed from captivity in Tehran began two weeks' leave with their families Saturday, while Iran's ambassador to London urged Britain to help his nation mend relations with the international community.

Ambassador Rasoul Movahedian told the Financial Times newspaper in an article published Saturday that Iran had "showed our goodwill" by freeing the Britons.

"Now it is up to the British government to proceed in a positive way," he was quoted as saying. "We will welcome in general any steps that could defuse tensions in the region."

The British mariners, captured in the Persian Gulf on March 23, were freed Wednesday by Iranian President Mahmoud Ahmadinejad, who called their release a gift to Britain.

Movahedian told the Financial Times that the release of the British crew was not connected to the fate of five Iranians held by U.S. forces in Iraq. U.S. officials said last week that Iran would be granted access to the detainees, but denied the decision was linked to the fate of British crew. Britain also has denied a link.

But Movahedian indicated help from the British on the matter would be appreciated.

"If they want to be helpful and use their influence we will welcome that. ... We will welcome in general any steps that could defuse tensions in the region," he said.

Movahedian called on Britain to use the resolution of the crisis as a chance to "establish sensible lines of communication with Iran."

He said "the prime issue for Iran" was recognition from the West of its right to a nuclear power program.

The United States and allies, including Britain, fear Iran is pursuing a nuclear weapons program under cover of its civilian nuclear program. Iran denies this, insisting it seeks to use the program only for nuclear energy.

Britain's Foreign Office had no immediate comment on the Iranian ambassador's remarks. A spokesman said officials "will need time to assess the implication for diplomatic relations with Iran" of the crew's accounts of their treatment in detention.

The newspaper said Movahedian spoke before several crew members described Friday how they had been blindfolded, bound, kept in solitary confinement and subjected to psychological pressure during their captivity.

On Saturday, the Vatican said that Pope Benedict XVI had written to Iran's supreme leader, Ayatollah Ali Khamenei, to intercede for the release of sailors. Vatican officials declined to give details about the letter, including when it was sent. The Vatican said the pope intervened for humanitarian reasons.

The sailors said during their Friday press conference that they were coerced into saying they had been in Iranian waters when they were detained.

"All of us were kept in isolation. We were interrogated most nights and presented with two options. If we admitted that we'd strayed, we'd be on a plane to (Britain) pretty soon," said Lt. Felix Carman, who commanded the crew. "If we didn't, we faced up to seven years in prison."

Marine Joe Tindell said he believed one of his colleagues had been executed on the second day of the ordeal. The 21-year-old said the crew believed they were being taken to the British Embassy to be released, but were instead dumped in a holding facility.

"We had a blindfold and plastic cuffs, hands behind our backs, heads against the wall ... there were weapons cocking," Tindell told British Broadcasting Corp. radio. "Someone said, I quote, 'Lads, lads I think we're going to get executed' ... someone was sick and as far as I was concerned he had just had his throat cut."

Iran dismissed the news conference as propaganda — just as Britain had condemned the crew members' frequent appearances on Iranian TV during their captivity.

The British crew was detained while patrolling for smugglers near the mouth of the Shatt al-Arab, a waterway that has long been a disputed dividing line between Iraq and Iran.

Tehran says the crew was in Iranian waters. Britain insists its troops were in Iraqi waters working under a U.N. mandate.

Prime Minister Tony Blair has insisted Britain did not negotiate for the sailors' release, and did not offer an apology for their alleged trespass into Iranian waters.

Despite the resolution of the crisis, tensions in the Persian Gulf remain high. The U.S. has two aircraft carrier groups off Iran's coast, its largest show of force in the region since the 2003 invasion of Iraq.

The Guardian newspaper reported Saturday that the U.S. military offered to mount "aggressive patrols" over Iranian Revolutionary Guard bases after the sailors and marines were captured.

The newspaper, which did not name its sources, said Britain had declined the offer and asked the U.S. to tone down its military activity in the Gulf. The Guardian said U.S. forces "modified their exercises to make them less confrontational."

The Foreign Office declined to comment on the report.