Two British-Australian women and an Australian man have been detained in Iran, it has been reported.
The Times said one of the women was arrested with her boyfriend 10 weeks ago on unknown charges while another woman was jailed for 10 years.
Iran has held several dual nationals in recent years, including the British-Iranian Nazanin Zaghari-Ratcliffe.
Australia’s foreign ministry confirmed assistance was being given to the families of the Australians being held.
The two cases are not thought to be linked.
The paper reported that the two women are believed to be the first British passport holders without dual Iranian nationality to be held in the country in recent years.
They are understood be in Tehran’s Evin jail, where Mrs Zaghari-Ratcliffe, 41, a mother of one from London, has been held on spying charges since 2016. She denies the allegations.
One of the women being detained is reportedly a blogger who was travelling through Asia with her Australian boyfriend.
It is claimed the second woman is an academic who had been lecturing at an Australian university.
While the charges against the second woman remain unclear, 10-year terms are routinely given in Iran for spying charges, the Times said.
The Foreign Office (FCO) said the Australian Department of Foreign Affairs and Trade (DFAT) was leading on the cases. The DFAT told the BBC it would not comment further after confirming it was providing consular assistance.
The Australian government said its travel advice for some parts of Iran was that it was not safe to travel.
It warns “there is a risk that foreigners, including Australians, could be arbitrarily detained, or arrested”.
The FCO website also warns of the risks from travelling in Iran. “The security forces may be suspicious of people with British connections,” it states.
Iran’s judiciary said last month that it had sentenced a British-Iranian dual national to 10 years for allegedly spying for Israel.
Anousheh Ashouri was detained over allegations he was working for the Mossad intelligence agency. He was also given an additional two-year jail term for illicitly acquiring money and fined $36,600 (£29,850).
Relations between the UK and Iran have been strained in recent months by a row over the seizure of oil tankers.