A British YouTube star was detained at a Russian-controlled space centre in Kazakhstan.
Travel blogger Benjamin Rich, who has more than 3.5 million subscribers, was held near one of the launch pads at the Baikonur Cosmodrome with his female friend Alina Tseliupa.
Dmitry Rogozin, who is the head of the Russian space agency Roscosmos, said local authorities were determining “the exact level of participation in illegal activities” by the pair.
Rich runs a YouTube channel called Bald and Bankrupt where he shares videos from some of the most remote and dangerous places in the world.
His last video was filmed in Syria and released on his channel last month.
Mr Rich posted on Instagram to reveal he had been released, along with footage of him showing off buildings in the former closed Soviet city.
The blogger said he had been fined by authorities following his detention.
"I’ve woken up to a load of messages asking me if I’m OK. Apparently people think I’m in a gulag because of some Twitter post," he said.
"Basically I was questioned by Russian police for a few hours for going to see the Buran rocket without the special permission and given a £60 administrative fine just like hundreds of foreign adventurers before me.
"The police also were nice enough to show me the closed town of Baikonur. Has an awesome mosaic of a Cosmonaut. Currently lying in my hotel room watching TC and eating Doshirak (red of course)… Hardly a gulag."
Baikonur is now open to tourists who apply for permission from the Russian space agency Roscosmos.
It sits around 1,100km (680) miles southwest of the capital of Kazakhstan, Nur-Sultan.