Undated handout photo shows retired FBI agent Robert Levinson. His family received these photographs in April 2011.
FILE - Undated handout photo shows retired FBI agent Robert Levinson. His family received this photograph in Apr. 2011.

Fears are mounting about the plight of more than a dozen Britons and Americans imprisoned in Iran. The U.S. and British governments accuse Tehran of holding them as "bargaining chips."

The detainees, their families say, could face longer prison time as a result of the confrontation between Washington and Tehran over the U.S. killing of Iranian General Qassem Soleimani.

FILE - An undated handout image shows Nazanin Ratcliffe and her daughter, Gabriella.

Nazanin Zaghari-Ratcliffe, the British-Iranian woman imprisoned in Tehran on what the British government says are trumped up espionage charges, is “in despair, definitely distraught,” according to her husband, Richard Ratcliffe.

He told the BBC, “We’re really worried as to what is happening ... we’ve always been a chess piece in this game, and we’re looking to the prime minister to make really clear that protection of Nazanin and others like her is a top priority.”

FILE -- Richard Ratcliffe husband of imprisoned charity worker Nazanin Zaghari-Ratcliffe, poses for the media during an Amnesty International led vigil outside the Iranian Embassy in London, Jan. 16, 2017.

He said that during a telephone call with his wife, the 42-year-old mother told him she and about 15 British and American inmates being held at Tehran’s Evin prison believe they will be used as pawns in the unfolding volatile standoff. “Nazanin was very bleak that Iran would now keep her and the others to serve their full sentences and more,” said Ratcliffe. “It is a game of poker where the stakes have suddenly gotten very high, too high for anyone to still be bluffing. That is tough to watch for all those of us caught in the middle,” he said.

Zaghari-Ratcliffe was arrested at Tehran airport in 2016 while on a family trip to introduce her infant daughter, Gabriella, to her Iranian grandparents. At least five U.S. citizens, also mostly dual nationals, are imprisoned in Iran. Some were detained before U.S. President Donald Trump took office.

Another American, former FBI agent Robert Levinson, vanished in Iran more than a decade ago. In June, Nizar Zakka, a Lebanese citizen and permanent U.S. resident, was freed after being held in an Iranian prison for nearly four years. His release came after lobbying by Lebanese and U.S. diplomats.

FILE - The seven children and wife of Robert Levinson, an American missing in Iran since 2007, appear outside U.S. District Court in Washington, Dec. 4, 2019, as they sue Iran for damages for his disappearance.

Like their British counterparts, the families of American detainees are also becoming more anxious. Joanne White, whose son, Navy veteran Michael White, was imprisoned in Iran in July while visiting a girlfriend, told the Associated Press, “He wasn’t safe before now, but now he’s really not safe.” Michael White was convicted of insulting Iran’s Supreme Leader. His mother says he has cancer and recently complained to her that he was starving in prison.

The Trump administration and the British government have made prisoner releases a key demand with Iran. Washington and London say the detainees are being held or have been convicted on false charges or arrested for use as hostages. Their families, though, fear the plight of their loved ones will fade into the background in the escalating crisis.

On Sunday, Secretary of State Mike Pompeo tried to reassure them that would not be the case. He told NBC’s "Meet the Press" program that the Trump administration was still working to secure the freedom of Americans in Iranian jails. “We continue to work on that process, to get every American held anywhere in the world, including by the kleptocrats and theocrats in Iran, to get them to return American hostages. We will never give up on that mission,” he said.

Detained British-Iranians include Anousheh Ashouri, a businesswoman, Morad Tahbaz, an ecologist, and Kameel Ahmady, a social anthropologist. Also held is Kylie Moore-Gilbert, a British-Australian academic. Iran refuses to recognize dual nationality for its citizens.

Zaghari-Ratcliffe’s husband appealed this week for British Prime Minister Boris Johnson to meet him and the relatives of other detainees.

“We are looking to the prime minister to make really clear that the protection of citizens like Nazanin and the others who are held is top priority for him,” he said. He urged Johnson to tell Trump, “His policy needs to be an awful lot clearer strategically.” Zaghari-Ratcliffe is midway through a five-year sentence, but was refused parole last month.

Dominic Raab, Britain’s foreign secretary, urged Iran Tuesday to free her and other Britons wrongfully imprisoned. He condemned Tehran for what he described as its “increasingly callous and cold-hearted treatment.”

In October, Australia secured the release of two of its citizens, Jolie King, a British-Australian blogger, and her boyfriend, Mark Firkin, in an apparent prisoner swap after it released an Iranian scientist detained for allegedly breaching U.S. sanctions. Washington had requested the Iranian, Reza Dehbashi, be extradited to the U.S. The Australians were arrested in July for flying a drone without a permit and King’s family members said the Iranians made it clear that she was being held as potential collateral for a prisoner swap.

Last month, the French government reacted angrily to Iran's detention of two French academics. It called for them to be released “without delay,” and urged Iran to show “total transparency.”