On Twitter, bots are accounts that are run remotely by someone who automates the messages they send and activities they carry out.

Some people pay to get bots to follow their account or to dilute chatter about controversial subjects.

As The BBC reports, UK researchers accidentally uncovered the lurking networks while probing Twitter to see how people use it.

The network of 350,000 bots stood out because all the accounts in it shared several subtle characteristics that revealed they were linked. These included:

tweets coming from places where nobody lives

messages being posted only from Windows phones

almost exclusively including quotes from Star Wars novels

It was "amazing and surprising" to discover the massive networks, said Dr Shi Zhou, a senior lecturer from UCL who oversaw Mr Echeverria's research.