The investigation is focused on a speech broadcast in August 2016.
Muttahida Qaumi Movement (MQM) founder Altaf Hussain was arrested in a police raid in London on Tuesday.
“A man has today, Tuesday, 11 June, been arrested in connection with an investigation into a number of speeches made by an individual associated with the Muttahida Qaumi Movement (MQM) in Pakistan,” the Metropolitan Police said in a statement, without naming Hussain.
“The man, who is aged in his 60s, was arrested at an address in north west London. He was arrested on suspicion of intentionally encouraging or assisting offences contrary to Section 44 of the Serious Crime Act 2007,” the statement added.
The investigation, which is being led by officers from the Met’s Counter Terrorism Command, is focused on a speech broadcast in August 2016 by an individual associated with the MQM movement in Pakistan as well as other speeches previously broadcast by the same person.
Hours after Hussain delivered the incendiary speech, MQM workers had attacked the ARY News office in Karachi. Shortly after, the Rangers had detained a handful of senior MQM leaders overnight, Dawn said in a report.
In the days that followed, the Karachi wing of the party led by Farooq Sattar distanced itself from Hussain and the London wing, the Dawn report added.