Update 2.10pm: A seven-year-old boy missing since the Barcelona attacks has been found alive in hospital, The Guardian is reporting.
Julian's aunt Hayley has posted a desperate appeal online to help find her nephew. "Please like and share", she said.
"Sadly I must tell you that we do believe that a number of British nationals were caught up in the attack and we're urgently looking into reports of a child believed missing who is a British dual national", May said in a televised statement from Downing Street.
"Julian is 7-years-old and was out with Jom when they were separated, due to the recent terrorist activity".More news: Kylie Jenner Talks About Her Breakup With Tyga in "Life of Kylie"
News Corp Australia has contacted DFAT for a response on the status of the boy and his mother.
After Mr Cadman made a plea for information, Prime Minister Theresa May said United Kingdom authorities were "urgently looking into reports" that a child, who has dual British nationality, is missing.
In the second attack, a gang wearing suicide belts rammed civilians with a auto before being shot dead by police.
Fears are growing for a young boy with links to the United Kingdom who is missing after the attack in Barcelona.More news: South Korea hints it'll consider envoy to North
Of the eight Australians impacted by events in Barcelona, Ms Bishop said four were injured, three required consular support and one is unaccounted for.
His mother Jom Cadman, who was separated from him during the attack, has been found in hospital.
The police force for Spain's Catalonia region says the five suspects shot and killed in the resort town of Cambrils were carrying bomb belts, which were detonated by the force's bomb squad.
Firearms were removed from the scene and belts they were carrying are being treated as potential explosive devices.More news: Mets trade Curtis Granderson to Dodgers
Separately, six civilians and one police officer were hurt when a vehicle drove into people in the town of Cambrils in a second attack.
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