(CNN) An Australian university lecturer detained in Iran has been sentenced to 10 years in prison for spying, a source with knowledge of the matter told CNN Wednesday.

Last week, the Australian government confirmed that University of Melbourne lecturer Kylie Moore-Gilbert was one of three Australian nationals currently detained in Iran.

Speaking Monday, Iranian Foreign Ministry spokesman Sayyed Abas Mousavi said that one Australian "has been sentenced to prison last year for espionage." The following day, however, Iranian judiciary spokesman Gholamhossein Esmaili appeared to contradict his colleague, saying Moore-Gilbert had been "spying for another country," but said her case still had to go to trial.

Responding to Esmaili's comments, the source reiterated to CNN that Moore-Gilbert -- a British-Australian dual citizen -- had already been tried and sentenced to ten years in prison. She has already been held in Iran for almost a year, the source said.

Australian Kylie Moore-Gilbert has been held in Iran for almost a year.

Separately, Elsami also on Tuesday confirmed the July arrest of an Australian couple who have been held for almost three months are accused of photographing military sites and other "forbidden areas." He said the photos had been taken on a drone.

Previously, the couple were identified as Jolie Ellen King and Mark Firkin, who have been documenting their world travels on YouTube and Instagram. A source familiar with the matter told CNN that King is a British-Australian dual citizen.

According to the ABC, the couple were arrested on the hills outside Iran's capital, Tehran. In Iran, a permit is required to operate a drone that can take photographs.

Jolie King and Mark Firkin in India, in a photo posted on Instagram on December 29, 2018.

Australia's efforts

Speaking Wednesday, Australia's Minister for Trade Simon Birmingham said Canberra has been supporting the three detained people for "some time now."

"We are concerned for the welfare of these individuals and work to make sure their treatment is as fair as possible," he told ABC's AM show . "We will show restraint when it comes to our public commentary around individual cases because often that is the best way to provide support for those individual circumstances when providing consular assistance."

In a press conference the same day, British minister Liz Truss said that London was "very concerned" about the issue.

A source familiar with the matter said that although two of the three are dual UK citizens, Canberra has been taking the lead on securing their release.

Australia currently advises citizens considering visiting Iran to "reconsider your need to travel," due to "the risk that foreigners, including Australians, could be arbitrarily detained or arrested."

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Rising tensions

News of the Australians' detention comes amid rising tensions between Iran and the United States and its allies, including Australia and the United Kingdom.

An attack on the Saudi oil industry over the weekend had a "very high probability" of having been launched from a base in Iran close to the border with Iraq, a source familiar with the investigation told CNN this week . Washington has ruled out a "knee jerk" response to the attack , but Pentagon officials have been ordered to plan a potential course of action.

Since the decision by US President Donald Trump in 2018 to walk away from a multiparty nuclear deal with Iran, Washington has attempted to use what it calls "maximum pressure" against Tehran.

Earlier this year, tensions between the US and Iran soared to levels that prompted fears of a conflict. Oil prices jumped as investors feared that attacks on oil tankers risked a disruption of shipments in the Strait of Hormuz, which passes by Iran and is key to the global supply of oil.

Last month, Australian Prime Minister Scott Morrison announced the country's defense force would work alongside the US and the UK on a maritime security mission in the Strait of Hormuz.