Meanwhile, the University lecturer has so far been in jail for nearly a year.
"It does sound extremely concerning and of course the UK government will do everything we can to support any UK British citizens who are caught in Iran", British Secretary of State for Business Andrea Leadsom told Sky News.
One of many ladies, a blogger who became travelling through Asia alongside with her Australian boyfriend, became arrested 10 weeks in the past on costs which dwell unclear, The Times reported on Tuesday.
The Foreign Office said it was clear the ship's cargo had been transferred to the Assad regime in an "unacceptable violation" of global trade sanctions.
The couple were reportedly rounded up and taken to an Iranian jail over two months ago, while the academic, who is said to teach at an Australian university, had been arrested several months ago, according to a source cited by the Guardian.More news: Stocks Gain on Global Trade Optimism, ECB Stimulus: Markets Wrap
The three are incarcerated in the Evin jail in Tehran.
The Australian government has confirmed reports that two British-Australian women and an Australian man have been detained in Iran and that the families of the three are receiving assistance.
Though the charges against the second woman remain unclear, Iran routinely hands out 10-year terms for spying charges, the Times said.
"Due to our privacy obligations, we will not comment further", he added.
Earlier this week the Australian government updated its travel advice for Iran to "reconsider your need to travel" and "do not travel" to areas near the border with Iraq and Afghanistan.More news: Marc Thiessen: Trump's Taliban Invite Insults 9/11 Victims
Those detained in the past 18 months include U.S. Navy veteran Michael White, arrested in July 2018; Morad Tahbaz, a British-Iranian businessman who was held in January a year ago; and Aras Amiri, an Iranian with British residency who worked at the British Council in London and was arrested in late November 2018.
The Foreign Office has warned dual Iranian citizens not to travel to Iran.
Meanwhile, Australia's public broadcaster ABC also reported that a third Australian national - the partner of one of the women - had also been detained.
"Iran once again ups the stakes" with the latest arrests, said Tulip Siddiq, Zaghari-Ratcliffe's member of parliament.
Their arrests come amid a downturn in relations between Britain and Iran, sparked by issues including the seizure by the Royal Marines in July of an Iranian oil tanker near Gibraltar.More news: Champion Kim Clijsters' shock return a very welcome one
The arrests come after Australia announced last month it would join the USA and Britain in deploying warships to the Strait of Hormuz.
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