Two teenagers have been charged as part of a National Crime Agency (NCA) investigation into a cyber attack on Transport for London.

TfL suffered a major hack on 31 August last year, which investigators believe was carried out by members of the cyber-criminal group, Scattered Spider.

Thalha Jubair, 19, from east London, and Owen Flowers, 18, from Walsall in the West Midlands, were arrested at their home addresses on Tuesday by the NCA and City of London Police.

Both appeared at Westminster Magistrates Court on Thursday afternoon charged with conspiring together to commit unauthorised acts against TfL, under the Computer Misuse Act.

When Mr Flowers appeared in court, he wore a grey hoodie with “off the grid” written on it. Mr Jubair sat next to him, wearing a black hoodie and black glasses.

Neither man spoke to each other during the proceedings.

Deputy Director Paul Foster, head of the NCA’s National Cyber Crime Unit, said: “Today’s charges are a key step in what has been a lengthy and complex investigation.

“This attack caused significant disruption and millions in losses to TfL, part of the UK’s critical national infrastructure.”

The hack disrupted TfL services for three months.

TfL wrote to around 5,000 customers to say there may have been unauthorised access to their personal information such as bank account numbers and sort codes.

Data including names, emails and home addresses had been accessed, TfL added.

Earlier this year, the NCA warned of an increasing threat from cyber criminal gangs based in the UK and other English-speaking countries, of which Scattered Spider is an example.