Britain's domestic intelligence service, MI5, is set to open an official Instagram account on Thursday, in the latest step by the country's spy agencies to come out of the shadows.

The Security Service, as it is formally known, will take the handle @mi5official, and use the account to bust popular myths and reveal never-before-seen archive material, the UK's Press Association (PA) reported.

MI5 also plans to host online Q&As serving intelligence officers and promote career opportunities on the Facebook-owned social network, which boasts more than one billion users globally, PA said.

The agency, once famous for approaching potential new recruits in discreet, shadowy encounters, began publicly advertising vacant positions in recent years. Historical exhibits from its museum, located in the basement of London headquarters by the River Thames near Westminster, will also be shared for the first time on Instagram.

The move comes months after MI5's new director-general Ken McCallum said he wanted the traditionally highly secretive agency to "open up and reach out in new ways". "Much of what we do needs to remain invisible, but what we are doesn't have to be," he said in his first media engagement in October, after taking up the job in late April.

"In fact, opening up is key to our future success," added McCallum, a MI5 veteran of more than 25 years who oversaw all counter-terror operations around the 2012 London Olympics. A 2018 parliamentary committee report strongly criticised the country's spy agencies for failing to reflect modern Britain and lacking women and ethnic minorities in senior positions. 

The UK's spy network also includes the Secret Intelligence Service (SIS) -- better known as MI6 and home of the world's most famous fictional spook, 007 James Bond -- as well as cybersecurity agency GCHQ.