A foreign national from Africa accused of posing as a soldier from the United States in order to groom a woman he met online, has been charged with fraud after allegedly scamming her out of almost $400,000.

Key points: A 34-year-old woman began an online romantic relationship with a man in October 2018 via social media

A 34-year-old woman began an online romantic relationship with a man in October 2018 via social media The man had a "well-structured backstory" as a US soldier and convinced her to give him close to $400,000

The man had a "well-structured backstory" as a US soldier and convinced her to give him close to $400,000 In a "disturbing" twist, the alleged scammer met with the woman, pretending to be an agent for the US soldier in order to collect the money

Police said the 34-year-old woman began an online romantic relationship with Cosmos Emeh, 32, after befriending him on social media in October 2018.

It is alleged in the following months, she was groomed into believing Mr Emeh was a US soldier, and sent him more than $200,000 through a money transfer service.

Police said he then travelled to the woman's house to collect a further $105,000.

Police will allege Cosmos Emeh pretended to be this American soldier to "catfish" the Brisbane woman. ( Supplied: Queensland Police )

She became suspicious and reported the matter to police after confiding in a close friend.

Detectives from the State Crime Command's Financial and Cyber Crime Group arrested Mr Emeh on Thursday while he was trying to persuade the victim to hand over more money.

He has been charged with one count each of fraud and attempted fraud.

The court heard Mr Emeh is studying a degree at a Brisbane university and denied having any contact with the alleged victim via the internet.

His lawyer told the court he only came into possession of the SIM card used to receive money and contact the alleged victim yesterday.

Mr Emeh appeared in the Brisbane Magistrates Court this morning where he was denied bail.

Police also executed a search warrant at a Durack home in Brisbane's west and seized a number of items.

Detective Inspector Vince Byrnes from the Financial and Cyber Crime Group said the alleged scammer had cultivated a "well-structured backstory" to deceive the victim.

"There was a backstory with this US military officer that involved the loss of close family members," he said.

"I would categorise this victim as a well-educated young person who has entered into an online relationship based on what she was told."

'Disturbing case'

Detective Inspector Byrnes said when the alleged offender met with the woman to collect money, he pretended to be an agent for the US soldier.

He said the in-person pick up was particularly "disturbing".

"It's very uncommon in Australia or anywhere around the world to have an offender involved in a scam to physically present themselves for the collection of money," he said.

Detective Inspector Byrnes could not say if the woman would get her money back and said police were investigating whether the accused had targeted other victims.

"This is a serious crime that has been perpetrated against somebody which can have a devastating emotional and financial effect upon them," he said.

"In circumstances like this, these generalised type of scams are not limited to one victim."

Detective Inspector Byrnes said people needed to be aware of the "red flags" when forming relationships online.

"The camera doesn't work on their phone so you can't Skype, you can't do it face-to-face — it's these types of methodologies used by the scammers to protect their identity," he said.

US soldier scam is common internationally

Detective Inspector Vince Byrnes said it was a particularly disturbing case. ( ABC News: Tim Swanston )

Detective Superintendent Terry Lawrence said it was a common international scam.

"The US Army Criminal Investigation Command receives hundreds of complaints a month from people who find themselves involved in an online relationship with someone purporting to be a US soldier," he said.

"Usually the offender's interaction with the victim is all online, so this further step of traveling to the victim's home is certainly something we need the public to hear and be warned of today."

Police said the case was an "urgent warning" to the public to be wary of relationships developed online.

"Take the time to evaluate the relationship, talk to friends and other loved ones about your new relationship online — we are thankful the victim in this instance took this step," Detective Superintendent Lawrence said.